Iranian security forces fired tear gas at anti-government protesters as they tried to hold a demonstration in Tehran on March 8.

"Security forces blocked the roads to Enghelab (Revolution) Square (in central Tehran) and fired tear gas at people several times as they tried to stage anti-government demonstrations," AFP reported citing opposition website Kaleme.com.

Kalame.com said "heavy security force deployments in several of Tehran's main squares." Foreign media have been banned from on-the-spot reporting of any unauthorized gatherings.

The reports of the demonstration came after Kaleme.com said that opposition leader Mir Hossein Mousavi and his wife Zahra Rahnavard were at their home and not in jail as it had previously reported.

"In recent days it has become evident to Kaleme.com that Mrs Rahnavard and Mr Mousavi... are under house arrest and so the news of their transfer from their home to a detention centre needs to be corrected and we apologise to our readers," the website said.

The website of Iran's other main opposition leader Mehdi Karroubi said it had no new information about his whereabouts but believed he had been taken into custody.

"Unfortunately until this moment we have no information on the situation of Mehdi Karroubi and (his wife) Fatemeh Karroubi," his Sahamnews.org website said. "According to strong evidence, we believe he is not at home and has been transferred to an unknown location," it added, saying it had spoken to one of his relatives.

Kaleme.com stressed that Mousavi and his wife remained under house arrest, a sanction it described as "unethical and illegal." "Given the complete cutting off of their communications with the outside world... it does indeed constitute house arrest, something which so far no one in the judiciary has officially acknowledged," the website said.