ISTANBUL -- Turkish antiterrorism units arrested dozens of people in several cities early Tuesday as part of an intensifying crackdown against antigovernment protests that have persisted for weeks.
The semiofficial Anatolian news agency said 84 people were arrested in the sweeps aimed at "members of terror organizations who destroyed public property, incited the public and attacked the police." The names of the detainees, or the specific charges against them, were not released.
Lawyers for the detainees said that they believed the total number of protesters in custody had reached at least 176 people, and that the vast majority of the arrests were on charges of illegal gathering and had nothing to do with terrorism.
Among them were more than 60 members of a leftist group detained on illegal gathering charges overnight, a representative of the bar association in Istanbul said. The association said it knew of 20 other people who could be facing the more serious charge of belonging to an illegal organization.
In Ankara, the capital, the bar association estimated that there had been at least 23 arrests. And more than a dozen people were detained overnight in Eskisehir, a university town in northwestern Turkey where many students have joined the protests.
Faced with the widening repression, hundreds of Turkish protesters have adopted a new tactic in the last two days: standing still in public spaces, for hours at a time. The approach appeared to have been first employed on Monday by Erdem Gunduz, a performance artist who stood in the middle of Istanbul's Taksim Square for hours, facing an enormous portrait of Mustafa Kemal Ataturk, the founder of the modern Turkish state.
Mr. Gunduz told the BBC that he was practicing "silent resistance."
For a time, the authorities, possibly befuddled, left him alone, until night fell and the police detained several other people who joined Mr. Gunduz. Word of the protest spread on social media and television, and by Tuesday similar vigils were staged in different parts of Istanbul and beyond, including in Ankara. As Taksim Square filled on Tuesday afternoon with people who stood -- some with eyes closed, some reading, and some stationary for only a few moments -- the police also stood, and watched. Some officers took pictures.
Turkey's interior minister said on Tuesday that the authorities would not interfere in the protest, unless it "breaks public order."
But Prime Minister Recep Tayyip Erdogan has reacted with growing annoyance to the protests, which have given him his most serious domestic challenge in a decade and embarrassed him abroad. In recent days, Mr. Erdogan has seemed to rule out a compromise with a movement that started with protests against the planned destruction of an Istanbul park and that grew by tapping into broader complaints over what critics see as Mr. Erdogan's authoritarian manner.
The sweeps on Tuesday came after days of increasingly bellicose rhetoric from Turkish officials. On Monday, the interior minister, Muammer Guler, said that new regulations were being prepared to police social media outlets, aimed at people who use Twitter or Facebook, for "inciting people or coordinating and directing events that would cause social incidents or endanger material and physical public safety through manipulative, false news."
Separately, the deputy prime minister, Bulent Arinc, raised the possibility that the military could be called in to help quell the unrest.
Mr. Arinc said the "innocent protests had ended" and that the continuing demonstrations were illegal. If the police were unable to contain the unrest, he said, the army could be called in, Anatolian reported.
The suggestion of any role for the military accentuates the challenge the protests pose to the government. It also highlights both the transformations in Turkey during Mr. Erdogan's tenure and his opponents' criticisms that he wields too much power.
The military, which carried out three coups over the past 50 years and forced another government from power, was once regarded as the primary obstacle to civilian rule in Turkey.
Mr. Erdogan blunted its influence with constitutional and institutional overhauls, and two years ago, its commanders resigned after a crackdown by the judiciary -- solidifying the prime minister's hold on the state's institutions.
Mr. Arinc's comments suggest that the government remained convinced of the military's loyalty, but some protesters hope that soldiers can be swayed: When army vehicles were spotted in Istanbul during demonstrations last week, dozens of protesters who were trapped in a hotel by the police started chanting pro-military slogans, hoping the soldiers would intervene on their behalf, though they did not.
Mr. Erdogan on Monday offered his latest appraisal of the protests that have forced a public reckoning of his performance.
"Turkey's democracy has been put to a very important test," he said during a televised speech, adding that because of the country's strong foundations, "neither our economy nor our democracy was hurt in these attacks."
A poll released Monday suggested that Mr. Erdogan's popularity had fallen. According to the poll, by the Metropoll Strategic and Social Research Center, based in Ankara, Mr. Erdogan's approval rating dropped to 54 percent in June from 61 percent in April.
Monday brought more signs of a growing intolerance for protests. After days of violent clashes in Taksim Square, in Istanbul, a man stood for hours there on Monday in a silent vigil. A few other people joined him, until the authorities arrested several of the quiet protesters.
Ceylan Yeginsu contributed reporting.
This article originally appeared in The New York Times.