TORONTO — The main Iranian opposition leader’s top aide, who was arrested last week because of his investigations into the abuse of prisoners in the crackdown after the disputed election, has been released in what appears to be a sign of retreat by the hard-core conservative authorities running Iran.
The release of the aide, Alireza Hosseini-Beheshti, was reported Sunday by the semiofficial ILNA news agency. He is a highly regarded academic with Islamic revolutionary credentials who worked directly under the opposition leader, Mir Hussein Moussavi.
No explanation for the release was given. However, an Iranian source close to Mr. Moussavi, speaking on condition of anonymity for fear of retribution, said Mr. Beheshti’s freedom was secured only after immense pressure by senior politicians.
Mr. Beheshti’s arrest had seemed to illustrate the length the government was willing to go to silence its opposition. His father, Mohammad Beheshti, who was killed in an explosion in 1981, was one of the main architects of the 1979 Islamic Revolution and the country’s Constitution.
Along with other signs of intolerance by Iran’s authorities after the election, Mr. Beheshti’s arrest had led to speculation that Mr. Moussavi and another top opposition figure, Mehdi Karroubi, would be arrested.
Both ran in the June 12 election and have asserted that the incumbent, Mahmoud Ahmadinejad, won by fraud.
In what appeared to be a sign of support for Mr. Beheshti from other veteran figures, Hassan Khomeini, the grandson of Ayatollah Ruhollah Khomeini, the founder of the 1979 revolution, visited Mr. Beheshti at his home after his release on Saturday, ILNA reported.
Mr. Beheshti was the head of one of the two committees that investigated the torture allegations of detainees during the post-election protests.
The other committee was led by Mr. Karroubi, who has charged that prisoners were raped and sodomized.
Iran’s supreme leader, Ayatollah Ali Khamenei, referred to their allegations on Friday as “lies and rumors,” and he warned that the system would respond harshly “to those who challenged its principles.”
On Saturday a judicial panel ruled that the allegations of rape were baseless and that Mr. Karroubi’s proof was fabricated. However, the panel also said the government’s measures to extinguish criticism have alienated many influential religious and political figures.
A source close to Ali Akbar Hashemi Rafsanjani, a powerful politician whose family supported Mr. Moussavi’s campaign, on Sunday corroborated reports that Mr. Rafsanjani threatened to resign his posts a few weeks ago after Ayatollah Khamenei issued an order for Mr. Karroubi’s arrest.
It remains unclear why that order was never carried out, but it may reflect a continuing power struggle between Ayatollah Khamenei and Mr. Rafsanjani, who is the head of the Council of Experts, which has the legal power to dismiss the supreme leader.
Several Iranian Web sites sympathetic to Mr. Moussavi, including mowjcamp.com, reported last week that Hussein Nouri Hamedani, the only senior cleric to have congratulated Mr. Ahmadinejad, had expressed regret and had said he was “tricked” by Mr. Ahmadinejad’s supporters.
Senior clerics in Iran’s holy city of Qum have historically given religious legitimacy to the government. Mohsen Kadivar, a senior cleric and a visiting professor at Duke University, who has ties with clerics in Qum, said that the number of clerics who were withdrawing their support for the government was increasing.
“We have the progressive clerics who have criticized the post-election events and openly sided with the protesters,” he said. “But some of the more conservative ones have also shifted their support and have stayed away from government ceremonies in a sign of protest.”
It is possible that the government is delaying Mr. Karroubi’s arrest until after this Friday, the date of Iran’s annual pro-Palestinian rally, to avoid further tension. Protesters and opposition leaders, including Mr. Karroubi, have said that they will use the occasion to hold antigovernment street protests.