Defeated presidential candidates Mir Hossein Mousavi and Mahdi Karroubi as well as former president Mohammad Khatami met late Monday and called for the release of those arrested during the protests and in sweeps afterward, the report on Mousavi's official Web site said.
The meeting - the first of its kind by the biggest names in the reform movement - appeared to be part of an attempt to resuscitate the opposition after the crackdown unleashed by police, Revolutionary Guards and pro-government Basij militia shattered massive protests that sprung up after the election.
Police say 20 protesters were killed, hundreds injured and more than 1,000 arrested in the violence and in sweeps that followed. Since the clampdown, there have been no major street protests for more than a week.
The government has closed universities and dormitories, fearing a new round of protests on Thursday, which is the 10th anniversary of a 1999 attack by Basij and police on protesting students.
Mousavi on Monday vowed to continue his campaign against a government he said lacks legitimacy - but hinted he was dropping the strategy of protests and moving to political action, including forming a party.
The pro-reform camp says Mousavi was the real winner in the election and accuses Iran's ruling system of faking results that showed a victory for incumbent hard-line President Mahmoud Ahmadinejad. Karroubi came last in the official results.
Iran's supreme leader Ayatollah Ali Khamenei, who has the final say on all state matters, has publicly sided with Ahmadinejad.
Police say most of those arrested during the protests have been released. Still, dozens of protesters, pro-reform politicians and journalists are still being held, and arrests have continued.
"The useless wave of arrests must end immediately and all those detained without committing the least crimes must be released. Also, security and military forces must return to their bases," Mousavi, Karroubi and Khatami said in a statement after their meeting.
They said there was a need to "end the existing security state of affairs (atmosphere)."
"Continuation of this situation will only lead to radicalization of political activities," the tree said.
The statement also deplored "savage and shocking attacks" by pro-government Basij militia against protesters.
The three also denounced what they called "inhuman, illegal" confessions that state media have said some of the detainees have made. Iran's hard-line leaders have been trying to erase any lingering doubts about the legitimacy of Ahmadinejad's government by portraying the unrest as sparked by foreign meddling.
State media have reported that some detainees have confessed to what amounts to collaboration with foreign powers against the Iranian state. The opposition has said the confessions were obtained under duress.
Mousavi separately met family of a protester killed in post-election riots, saying innocent blood won't be wasted.
"Blood shed unjustly won't be wasted," the reformist Web site www.norooznews.net quoted Mousavi as telling the family Tuesday.