Human-rights groups and Iranians living abroad say the government has detained more opposition supporters and activists, including Salah Noghrekar, the nephew of opposition leader Mir Hossein Mousavi and legal advisor to his presidential campaign.

Opposition Web site Rah-e-Sabz is reporting that Grand Ayatollah Abdul Karim Mousavi-Ardebili traveled to Tehran from the holy city of Qom to plead with Supreme Leader Khamenei to release opposition protesters in government custody.

Iran's Deputy Police Chief Ahmad Reza Radan urged Iranians on state TV to cooperate with security forces to make Thursday's celebration of the Islamic Revolution go smoothly.

"It is necessary for people to cooperate in order to make the celebration take place in a secure and organized manner. Many people will be participating, so it is imperative to obey the law," he said.

Former French Ambassador to Tehran Francois Nicoullaud says that opposition leaders have urged their supporters to protest peacefully on Thursday, but he says it is not clear what will happen, since those leaders are more "figureheads," to a movement that is operating on its own.

"The leaders of the opposition have called upon their troops to go to the streets and demonstrate peacefully on the 11th of February. So, will they be listened to?" He wondered. "You know, [the leaders] are more figure-heads than leaders. The opposition moves through informal channels and not through hierarchical orders. This is a weakness for the opposition, because there is no central brain. But, this absence of organization makes it more difficult for the regime to develop counter-tactics," said the former diplomat.