Protesters demanding change have clashed with Iran’s security forces for the second day running.
At least four demonstrators were shot dead in Tehran according to an opposition website. A senior police official has denied this. Some police are now refusing to shoot at protesters, according to the opposition.
Authorities warned pro-reform activists against using this weekend’s religious festival of Ashura to revive protests against the clerical establishment.
But the latest pictures of clashes and casualties appear to show those warnings have not been heeded.
Separately, pro-government activists are said to have organised a counter-demonstration in Tehran. It is difficult to verify information because of restrictions on foreign media.
In a further sign of escalating tension, a pro-government militia disrupted a speech being given by reformist ex-President Mohammad Khatami in a Tehran mosque. Panic broke out on Saturday night as dozens of people, reportedly armed with pepper spray, chains and batons burst in.
Khatami, who backs opposition leader Mirhossein Mousavi, had to leave before being able to finish his address.
The Islamic Republic has seen the worst unrest in its 30-year history since June’s disputed presidential election that returned Mahmoud Ahmadinejad to power.