They blame him for the storming of a student dormitory which triggered the wave of protests - the most violent disturbances since the early years of the Islamic Revolution.

"To prevent further damage to the whole establishment, to sympathise with the families of the victims, and to respect the wounded sentiments of the Iranian nation ... we ask you to resign as head of the security forces," the students said in a letter to him.

The students say they will not call further demonstrations while they are seeking meetings with the country's leaders.

But they are demanding that responsibility for security in the capital be transferred to President Khatami's reformist government from the office of the supreme leader, Ayatollah Ali Khamenei.

The students say 1,400 people have been arrested in the disturbances. Hardline officials have said they may face trial as counter revolutionaries, a charge which carries the death penalty.

BBC Middle East correspondent Jim Muir says the student demands have the support of reformist factions, but in the heated atmosphere of accusations and recriminations which has followed the street riots, it remains to be seen how far they will get.

Since the riots, security control in Tehran has been largely taken over by the volunteer Basij forces, an armed civilian auxiliary of the revolutionary guards.

The unrest began after the temporary closure of the liberal Salam newspaper last week and the introduction of new legislation to curb Iran's free press.