BEIRUT, Lebanon -- A right-wing newspaper close to Iran's supreme leader yesterday accused the country's main opposition figure of being a dupe for Iran's foreign enemies and said he should face trial.

But Mir-Hossein Mousavi, defeated presidential candidate and leader of a nascent reform movement, remained unbowed. The soft-spoken but defiant former prime minister responded by releasing his most detailed account yet of what he maintains was vote-rigging and irregularities in last month's re-election of President Mahmoud Ahmadinejad, including an allegation that only the incumbent's allies were allowed to witness vote-counting election day.

"None of the [opposition] candidates' representatives were allowed to go in," the three-part report states.

In a sign of potential escalation of Iran's confrontation with the West, an Iranian military official said the "ground has been set" for a takeover of the British Embassy residence in north Tehran. Iranian officials have accused Britain of stirring up the large-scale public protests that roiled Tehran for several weeks after the June 12 vote.

The crackdown continued against supporters of the opposition accused of taking part in recent protests. The Web site of state-owned Press TV reported that 35 people were arrested. In Tehran, police have begun summoning residents to warn that they would be arrested if they did not stop rooftop protest chants that have become a nightly ritual of defiance throughout the capital and other cities.

The moves are the latest steps by authorities to silence critics and paint the recent weeks of political discord as the work of foreign agents and criminals.

They also are part of an official attempt to blame the opposition for days of violence that most witnesses and independent observers say was provoked by security forces and militias loyal to supreme leader Ayatollah Ali Khamenei, an Ahmadinejad ally.

The state-owned newspaper Kayhan, long considered a mouthpiece of Ayatollah Khamenei, Iran's highest political and religious authority, yesterday described "undeniable facts and documented evidence" that Mr. Mousavi was a foreign agent on "a mission directed from abroad."

Hossein Shariatmadari, a hard-liner loyal to Ayatollah Khamenei and a staunch Ahmadinejad supporter, penned the piece, which represents a further effort to stigmatize a movement that was built on Mr. Mousavi's political campaign.