Iranian police have fired tear gas to disperse opposition supporters mounting protests in the capital Tehran.
A BBC correspondent in Tehran has reported that large numbers of riot police and militia on motorcycles in the city centre broke up any crowds that formed.
The opposition Kaleme website said security forces and "people in civilian clothes" tried to disperse the crowd.
The unrest came a day after websites close to opposition leaders Mir Hossein Moussavi and Mehdi Karroubi said they had been jailed.
The government has denied this, saying the opposition leaders are at home.