REUTERS and other sources, Iran's judiciary denied on Monday reports that two opposition leaders, Mirhossein Mousavi and Mehdi Karoubi, had been arrested, the semi-official Fars news agency reported.
"The two are currently in their homes and there have only been restrictions on their contacts," Fars quoted an unnamed judiciary official as saying.
But International Campaign for Human Rights in Iran, indicates a serious escalation in the Iranian government's effort to silence the opposition movement that grew out of protests over the disputed presidential election in June 2009.
Kaleme.com said Mousavi, his wife Zahra Rahnavard, as well as Karroubi and his wife, Fatemeh Karroubi, were transferred to Heshmatieh prison in the Iranian capital. The men had been under house arrest for more than two weeks. The report said it was not immediately clear when they were transferred to the prison.
In Iran, activists and opposition members have demanded that Mr Mousavi and Mr Karroubi be released, vowing to stage demonstrations every Tuesday until they are freed.