Iranian security forces have reportedly fired tear gas and clashed with opposition supporters in Tehran gathered to demand the release of two major opposition leaders thought to have been shepherded last week from house arrest into prison.
An eyewitness interviewed by RFE/RL's Radio Farda said two major downtown streets, Enghelab (Revolution) and Azadi, were full of protesters.
Police were reportedly trying to stop people from reaching main streets through the use of tear gas. The same eyewitness said a number of protesters had been arrested.
It was unclear how many protesters defied warnings against "illegal gatherings," but reports said thousands of demonstrators had gathered at various points in the capital.
Reports also said large numbers of security personnel were stationed in central Tehran in an apparent effort to prevent opposition supporters from gathering.
Witnesses said ‘dozens’ of demonstrators have been arrested in the capital. Radio Farda reported eyewitness accounts of violent protests between security forces and protesters in Mashhad and Shiraz, where an eyewitness said “three van loads” of people had been arrested so far.
Protesters yelled slogans such as "Death to the dictator" and in favor of opposition leaders Mir Hossein Musavi and Mehdi Karrubi.
In Tehran, security agents and police forces hit back hard, using tear gas to disperse protesters. Police also blocked traffic on streets where protesters had gathered.
Meanwhile, the opposition website "Neda-ye Sabz-e Azadi" said the security section of Tehran University had suspended lectures in several departments in a move seen as an attempt to keep students away from the university.
There were also reports that after the number of protesters swelled, especially in the district near the prison and Tehran University, security forces began using electric batons to beat back demonstrators.
Opposition website Kaleme.com, which is close to Musavi, has reported that he and reformist cleric Karrubi were recently thrown into in a Tehran prison. Their wives, Zahra Rahnavard and Fatemeh Karrubi, were also reportedly jailed.
Iranian officials deny the reports of imprisonment but have not confirmed the whereabouts of the two men.
Iran's chief prosecutor, Gholam Hossein Mohseni Ejei, said the allegations by some "hostile" media were "false." As for the planned protests, Ejei said, "anyone who acts against the law will be dealt with."
A YouTube clip was uploaded of what is said to be opposition activists chanting "Allahu Akbar," or "God is great," from Tehran's rooftops overnight.
In Washington, White House spokesman Jay Carney called Iran's reported detentions "unacceptable" and urged that they be released.
British Foreign Secretary William Hague also called on Tehran to release both immediately, saying he was “deeply concerned” by the arrest reports, especially “given the inexcusable calls by Iranian parliamentarians for Musavi and Karrubi to be executed.”
Hague said ”the eyes of the world remain on the plight of opposition figures in Iran.”
The two opposition leaders had been under house arrest since calling for a February 14 rally in support of recent uprisings in Egypt and Tunisia. Two people were killed at the rally, which, although officially banned, reportedly attracted tens of thousands of protesters.
In recent days, Musavi's and Karrubi's children and neighbors have said that they seemed to have been moved out of their residences.
Kaleme, quoting what it called "credible sources," reported on February 28 that the arrest and transfer to jail of the opposition leaders and their wives is "certain" but the exact time of the move was not clear. The website said they are being held in Tehran's Heshmatiyeh jail.
Authorities have said all outside contact with the opposition leaders has been cut.
At his weekly news conference, Foreign Ministry spokesman Ramin Mehmanparast called the situation a "domestic issue" which was being used as a pretext by "America and some other Western countries...to try to divert everyone's attention to unreal issues."
An unnamed judiciary official was quick to deny the report in an interview with the hard-line Fars news agency that is said to have ties to Iran's Islamic Revolutionary Guards Corps.
"The two are currently in their house. There have only been some limitations on their contacts with suspicious elements," the official was quoted as saying.
However, Amir Arjomand, a senior adviser to Musavi, who is currently in France, confirmed the Kaleme report in an interview with RFE/RL's Radio Farda.
"It has been more than two weeks that Iranian authorities have put Musavi and Karrubi in a situation such that no one has any reliable information about their conditions and health," he said. "There have been many speculations. For us, after we investigated, the report about the transfer of Musavi and Karrubi and their wives to Heshmateiyeh is considered credible."
Karrubi family members were quoted by his website Sahamnews as denouncing attempts by the authorities "to justify illegal, immoral, and un-Islamic behavior" against the two opposition leaders.
Musavi's daughters issued a statement on Kaleme rejecting denials of the arrests. They said they will "only be in a position to deny the arrest and incarceration of our parents if we are able to have an immediate visit with them without threats and without the presence of security forces."
'Sitting On A Volcano'
Musavi and Karrubi have come under increasing pressure for challenging the disputed reelection of President Mahmud Ahmadinejad in June 2009 and for condemning the brutal postelection crackdown.
Chief prosecutor Ejei said the authorities had cut all outside contact with Musavi and Karrubi.
"As a first step, their contacts, such as meetings and telephone conversations, have been restricted," Ejei said. He added that "should circumstances arise, other measures will be taken." Ejei did not mention where the two are being held.
Abbas Milani, the director of the Iranian studies program at Stanford University, tells RFE/RL that Iranian officials are unlikely to confirm the news of the imprisonment of the two opposition figures.
The Iranian authorities "know that their regime is facing political turmoil," Milani says. "They know they are sitting on a volcano that is ready to erupt. They don't know what might be the spark that would [catalyze] the people."
The opposition movement had earlier announced a rally scheduled for March 1 in Tehran and other cities to protest the house arrest of Musavi and Karrubi.
The opposition website Neda-ye Sabz-e Azadi reported that the security section of Tehran University suspended lectures in several departments in a move seen as an attempt to keep students away from the university.
Unconfirmed reports also indicate that security agents on motorbikes have gathered around Enghelab (Revolution) Square, close to the university.
A student activist in Tehran told RFE/RL that the reported jailings of Musavi and Karrubi, whom he described as "very popular," could make opposition members "more determined" to take to the streets.
Iranian journalist Shahram Rafizadeh believes the opposition Green Movement will continue to challenge the Iranian establishment regardless of whether Musavi and Karrubi are under house arrest or imprisoned.
"On February 14, Musavi and Karrubi were prevented from attending the opposition rally, yet we witnessed that may people participated in the protest," he said. "The Green Movement will continue to be active and protest without leadership. It's one of the outstanding traits of the movement."
Milani of Stanford University says the arrest of the two opposition leaders, if confirmed, could lead to the "radicalization" of the opposition movement.
"With [Supreme Leader Ali Khamenei's] actions and comments, he is gradually closing all the doors to any reconciliation, any peaceful [solution] and arbitration between the majority of people who are against the establishment and the regime itself," Milani says. "Closing these doors is not going to put an end to the dissatisfaction. It will increase it."
With increasing dissatisfaction, he says, "an explosion" becomes more likely.
with contributions from RFE/RL's Radio Farda and Antoine Blua