MOSCOW -- Two have fled the country. Another is in jail, his oil empire in ruins. Russian President Vladimir Putin has largely succeeded in his campaign pledge to make oligarchs -- the powerful tycoons who emerged in the chaos of post-Soviet Russia -- disappear "as a class."

Now, most of the country's super-rich are either packing up or hunkering down and trying to stay on the government's good side.

Except Mikhail Fridman. Using bare-knuckles business tactics, the 41-year-old built an $8 billion empire spanning oil, telecoms, banking and retail. Now, he's picking a fight with Leonid Reiman, Russia's telecommunications minister and a longtime Putin friend.

Last fall, lawyers for units of Mr. Fridman's Alfa Group lined up Anthony Georgiou, a former Reiman partner, to provide testimony to a British Virgin Islands court that he'd paid over $1 million in bribes to Mr. Reiman. He testified that the payments happened when the future minister was a top executive at a Russian state phone company in St. Petersburg in the early 1990s. Based in part on allegations raised in the case, German prosecutors have opened an investigation into whether Western banks facilitated any criminal activity.

Mr. Reiman has strenuously denied any wrongdoing, and late last year accused Alfa of smearing him to prevail in a business dispute. "Alfa, because it's an old oligarchic structure, is trying to use the traditional means by which they've resolved conflicts many times over many years -- by putting pressure on officials," Mr. Reiman told reporters.

In fact, Mr. Fridman makes little pretense that this is just about clean government. He's in a vicious battle over a stake in Russia's No. 3 mobile-phone company. His lawyers are using the corruption charges to fight off a legal challenge from a Bermuda-registered investment fund that claims it owns the stake. Mr. Fridman has offered to drop the lawsuits if the other side agrees to settle.

In Russian business, where hostile takeovers often involve burly men with masks and submachine guns, toughness has long been a key to success. But Mr. Fridman, whose hardball tactics are legendary, is charting a lonely course of resistance at a time when the state is increasingly squeezing private business.

"It's our style, our strategy and we're not changing it. We do a lot of things that might seem aggressive to some people," the baby-faced Mr. Fridman says with a smile, sitting in his spartan white office in downtown Moscow.

So far, Alfa has managed to avoid trouble with the Kremlin itself. Mr. Fridman has tried to insulate himself by hiring former top government officials as advisers, including Pyotr Aven, a former trade minister and an old friend of Mr. Putin who meets the president regularly.

Mr. Fridman says he's careful to avoid anything that the Kremlin would see as a challenge to its control of national politics. That's widely believed to be what got billionaire Mikhail Khodorkovsky in trouble: He was contributing tens of millions of dollars to a broad range of political parties. He's now serving an eight-year prison sentence on fraud and tax-evasion charges. His OAO Yukos oil company was slapped with $28 billion in back-tax claims and largely nationalized last year.

Where Mr. Khodorkovsky was often openly critical of the Kremlin during his frequent trips to the U.S., Mr. Fridman is much more careful. In January, he flew to New York to open a lecture series his bank endowed at the Council on Foreign Relations. The speaker was Russian Defense Minister Sergei Ivanov, a Putin confidante and a man frequently tipped as a potential presidential successor. Mr. Fridman introduced him as "an outstanding politician."

Alfa also has lined up some high-profile insurance. The oil company it controlled is now half-owned by BP PLC, in a deal for which Mr. Fridman made sure to get public backing from Mr. Putin and United Kingdom Prime Minister Tony Blair. In the wake of the Yukos case, which has battered business confidence and badly tarnished Mr. Putin's international reputation, Mr. Fridman says he doesn't think the Kremlin will risk another open clash with big business.

Still, these days every new back-tax claim against a company linked to Alfa spurs a wave of speculation in the local press that Mr. Fridman is about to face the same fate as Mr. Khodorkovsky.

A devoted movie and theater buff, Mr. Fridman is also known to take a turn at the piano at Color of the Night, the Moscow jazz bar he owns. He still looks a bit like the nerdy kid from school, his brown hair untouched by grey. The self-described adrenaline junkie has a taste for adventure that extends beyond the office to annual off-road rallies through the jungles and deserts of Africa, Asia and Latin America.

Public information about the Alfa Group is limited, since it's a private company owned by Mr. Fridman and two university friends. Run roughly like a giant private-equity fund, the group holds assets valued at about $20 billion, says Mr. Fridman, who adds that his stake is "more than 40 percent." The assets are owned by a complex web of holding companies located in discreet offshore jurisdictions like Gibraltar. Managers of the various businesses -- banking, oil, trading, retail and telecoms -- own minority stakes in the individual units, sometimes alongside outside partners.

"We're financial investors," says Mr. Fridman, who keeps an apartment in downtown Moscow and commutes regularly to Paris, where his wife and two daughters have lived since the early 1990s. "We don't consider ourselves experts in the industries we're in."

Colleagues say Mr. Fridman led the group's push in the late 1990s into the oil business, which now delivers most of the profits. Telecom has been the focus for expansion since then -- Russia has been among the world's fastest-growing wireless markets for the past several years. Mr. Fridman says he aims to cobble his stakes in the region together into a regional network and then negotiate an equity alliance with a global player like Vodafone Group PLC.

For Mr. Fridman, a Jewish kid from Lvov in what's now Ukraine, persistence has long been a business signature. As a student in Moscow in the 1980s, he says he was blocked from continuing his studies because of anti-Semitism in the Soviet education system. So he started a window-washing cooperative, becoming one of the first to take advantage of the chance to open a private business.

After the collapse of the Soviet Union in 1991, he built his fortune trading everything from Oriental rugs to Cuban sugar to Russian crude. As the government began privatizing thousands of state companies, Mr. Fridman pushed the group into the oil business. He lined up two Russian emigre partners who helped cobble together a patchwork of formerly state-owned companies into a group they called Tyumen Oil Co., known by its Russian abbreviation TNK.

It was a heady time for Mr. Fridman and his fellow oligarchs. They'd made millions as capitalism was just taking root in the early 1990s and used their fortunes to build vast political clout. In 1996, Mr. Fridman and a handful of tycoons teamed up to finance President Boris Yeltsin's 1996 re-election campaign. Using their close connections with the Kremlin, they snapped up the country's richest assets in often-rigged privatizations and, in some cases, were awarded with top government jobs. Boris Berezovsky, for example, whose interests ran from oil to television, was named deputy secretary of Russia's powerful Security Council.

Along the way, Alfa cemented its reputation for aggressive tactics. Alfa often took advantage of gaps in the bankruptcy law that allowed small creditors to take control of debtor companies.

Officials at Norex Petroleum Ltd., a small Canadian oilfield-services company, contend Alfa went a step further in 2000, when it moved to take control of a Siberian joint-venture Norex had with a TNK unit. In a lawsuit filed in U.S. District Court in New York, Norex alleges that TNK took over with 20 machine-gun-toting guards. One executive was quoted in the lawsuit as saying that a top Alfa official vowed to "run over (the company) like a steamroller" if they resisted. Alfa says it's confident that its takeover of the company was legal but won't comment on details of the case, which hasn't yet gone to trial. Norex is seeking to recover $1.5 billion.

But even as Alfa was still throwing its weight around, twilight was setting in on the era of the oligarchs. Mr. Putin came to power in 2000 vowing to reassert Kremlin authority. Within a year, two of the most politically influential oligarchs, Vladimir Gusinsky and Mr. Berezovsky, had left the country under threat of prosecution, leaving the bulk of their empires behind. Oil tycoon Roman Abramovich quietly began selling off his holdings and spent more and more time in London, where he bought Britain's Chelsea soccer team. Last month, state gas company OAO Gazprom announced a deal to buy the oil company he controls, OAO Sibneft, for $13.1 billion.

Sensing the winds shift, Mr. Fridman realized he needed to move fast to get a foreign partner for TNK, a move that would provide both political insurance and cash. "We knew at some point that opportunity would be gone," he says.

Tempted by Siberia's vast reserves, BP was already on the prowl for a Russian deal. But Alfa had to rebuild relations with the British giant that had soured in the late 1990s when Alfa, in a battle with another oligarch, stripped key assets out of BP's previous investment in Russia. Mr. Fridman patched things up with BP CEO John Browne. BP wound up paying $7 billion in 2003 for half of the oil company Alfa owned with two partners. "There is a toughness built into the culture of Russia," Mr. Browne said at the time. "You have to cooperate."

Mr. Fridman's timing was impeccable. Although analysts touted the BP deal as the first of many foreign investments in the oil patch, the Kremlin soon closed the door on such big deals with foreigners and geared up to attack Yukos.

But it wasn't long before Mr. Fridman got into a government-relations mess of his own. In a complex series of transactions in the summer of 2003, Alfa had bought a 25 percent stake in Megafon, Russia's No. 3 cellphone company. The stake had previously been owned by LV Finance, an investment firm controlled by Leonid Mayevsky, a former legislator.

Within days, a little-known Bermuda investment fund called IPOC International Growth Fund Ltd. contested the sale, claiming it was entitled to the shares under a pair of option agreements dating to 2001. IPOC went to court in Bermuda and the British Virgin Islands, where some of the Alfa companies holding the Megafon shares were registered. IPOC also launched arbitration proceedings against LV Finance in Switzerland, where the 2001 option agreements had been executed.

Lawyers for LV Finance, cooperating with Alfa's legal team, argued IPOC hadn't properly paid for the options. They also sought to convince the courts that IPOC was in effect a criminal enterprise, thereby rendering any of its contracts illegal and voiding its claim to the Megafon shares.

In written arguments in the BVI case, Alfa lawyers asserted that an affidavit from former IPOC President Vidya Sharma showed IPOC was "simply a front for laundering the proceeds of criminal conduct in Russia for ... Leonid Reiman."

Alfa lawyers argued in court papers in the BVI that IPOC was part of a complex network of companies that served to conceal Mr. Reiman's ownership of large stakes in Russian telecom companies, including Megafon. They alleged the fund got its money from corrupt dealings in Russia involving the minister.

IPOC denied the allegations and accused Alfa of paying witnesses. In fact, Alfa did pay $7 million to Mr. Georgiou, the former partner of Mr. Reiman. Alfa said the payment was to buy out most of Mr. Georgiou's Russian businesses, which he feared would suffer after his testimony.

Mr. Reiman denies any wrongdoing. Jeffrey Galmond, a Danish lawyer who has known Mr. Reiman since the late 1980s, has testified that he's the owner of IPOC and its related companies -- holdings that could be worth more than $1 billion. He says the corruption allegations are just an effort to distract from what he says is Alfa's fraudulent acquisition of the shares.

"It looks to me as an attempt simply to crush a competitor by Alfa," he told a civil proceeding in Geneva last year. "They are all over the place and there is, in my personal opinion, no limit to what they are capable of doing."

The conflict has been tense. At the Geneva hearing, the presiding arbiter complained his house was being watched and his garbage searched. He said police told him the surveillance was linked to the case, although the culprits were never caught. Acting on an IPOC complaint, Russian police are investigating possible fraud charges against Mr. Mayevsky for his role in the Megafon share sale. He briefly fled Russia to avoid arrest.

Mr. Galmond says he got the money for IPOC from a series of lucrative deals in Russian telecoms and real estate in the 1990s. In court testimony, he admits that Mr. Reiman's work "played an important part in the creation of my own success and wealth," but says that took place before Mr. Reiman became minister. Mr. Galmond acknowledges he bought a summer house on the Danish coast in 1993 that he says he and Mr. Reiman shared, but denies any wrongdoing.

Court rulings are still pending in most of the cases. Prosecutors in Frankfurt, tipped off in part by the allegations from Alfa and LV Finance, are already investigating whether Germany's Commerzbank AG, which worked with Mr. Galmond, was involved in money laundering as a result, according to a spokesman for the prosecutor. Commerzbank denies it broke any laws, but a senior executive involved in the case resigned this summer and the bank has vowed to tighten internal oversight.

So far, the Kremlin is showing no sign that it's concerned about the allegations. Last year, Mr. Putin even took the unusual step of intervening to restore Mr. Reiman's ministerial job when he was about to lose it in a government reshuffle. He'd left nearly all the other appointments to his prime minister to decide.

As the grudge match dragged on, some of Alfa's other investments in Russia ran into trouble. In December, telecoms company OAO Vimpelcom, in which Alfa owns a big stake, was told it owed $160 million in unpaid taxes and fines. Vimpelcom's American depositary receipts, which trade on the New York Stock Exchange, plummeted 30 percent in two days. The company later got the tax claim sharply reduced and the stock has recovered. And in April, authorities slapped Alfa's main oil investment with $790 million in back-tax claims for 2001.

But unlike Yukos, which was crippled by tax assessments and saw executives jailed, tax and regulatory problems so far haven't fazed Alfa or its companies. The regulatory issues have cleared up and in August, TNK-BP said it settled the tax claims for $250 million. Auditors are still looking at company taxes for 2002 and 2003.

Mr. Fridman says the Megafon fight is worth it: He estimates Alfa's stake is now valued at about four times the $300 million he paid for it in 2003.

"We understood that there would be unhappiness on the part of certain bosses in the telecommunications ministry, but we were ready for that," Mr. Fridman says, adding that Alfa's legal position is "ironclad."