An influential group of Iranian dissidents have issued an unprecedented declaration defending the right to criticise their leaders.
Protesters are split over what role the US should play
Following five nights of violent protests around Tehran University, the 248 reformists said the people of Iran had "the right to fully supervise the action of their rulers".
"Sitting or making individuals sit in the position of divine and absolute power is a clear heresy towards God and a clear affront to human dignity," said the strongly-worded statement.
US President George W Bush has meanwhile described the Iranian protests as "positive" and "the beginning of people expressing themselves toward a free Iran".
Both conservative and pro-reform members of the Iranian establishment have strongly condemned US support for the demonstrations, which are now reported to have spread beyond Tehran.
Participants have been criticising the conservative clerics as well as the reformist President, Mohammad Khatami, who is accused of betraying hopes for change.
Police have been deployed in large numbers to prevent vigilantes loyal to the conservative establishment from attacking the protesters.
At the culmination of violence on Friday night, chain and club-wielding vigilantes - which state radio described as "thugs" - broke into student dormitories beating up some of the students.
The dissidents' one-page statement was followed by two pages of names of its signatories, the AFP news agency reported.
They include Hashem Aghajari, a pro-reform dissident who is awaiting a revision of his death sentence passed last year after he questioned the clerics' right to rule.
Another signatory is dissident Ayatollah Hossein Ali Montazeri, the cleric once designated as successor to the Islamic Republic's founder, Ayatollah Khomeini.
The dissidents also support a recent letter by more 100 members of parliament who urged Ayatollah Khamenei to give way to reforms or risk the survival of the regime.
The BBC's Miranda Eeles in Tehran says this new unprecedented statement is likely to increase pressure on the ruling clerics who have been trying to control the demonstrations of the past five nights.
But conservatives and reformists have closed ranks to criticise what they call "flagrant interference" by the US.
There is no doubt that the US president has been seeking to encourage the anti-government protests in a country he has included in the "axis of evil", says BBC regional analyst Sadeq Saba.
But some Iranian opposition groups fear that direct US support could play in the hands of the hardliners in the regime, our analyst says.
Student associations have said they will continue to demonstrate until 9 July, to commemorate the violent attack by hardline groups on students four years ago.
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