In the Iranian capital Tehran, supporters of opposition leader Mir Hossein Mousavi have rallied at the university in the biggest display of dissent in weeks since the government crackdown on the presidential election protests.

Eyewitnesses say that tens of thousands of people have gathered to demonstrate. At least 15 arrests have been made, according to one witness. The demonstrators are, for a large part, clad in green - symbolic for support for Mr Mousavi.

At Friday prayers today, former President Ali Akbar Hashemi Rafsanjani called for the release of demonstrators who contested the result of the recent election. Mr Rafsanjani is an important political figure and cleric in Iran and has backed Mr Mousavi. During his sermon, which was broadcast on state radio, the former president said something had to be done to allay people's doubts about the result of the presidential poll and added that Iran was in a deep crisis.

There were chants of support for Mr Mousavi, who was reported to have attended the prayers. Mr Rafsanjani led the Friday prayers for the first time since last month's disputed election which gave President Mahmoud Ahmadinejad a second term in office. The cleric also attacked the way the authorities had handled the poll and its violent aftermath. It was vital to restore voters' faith in the system, Mr Rafsanjani said.

former Iranian president Akbar Hashemi Rafsanjani by Amir Farshad Ebrahimi (flickr)