The Iranian opposition leader who has become the face of a weeks-long protest movement appears to have bowed to political pressure by agreeing to seek permits before planning future rallies.

Mir Hossein Mousavi, who lost the controversial recent election to President Mahmoud Ahmadinejad, maintains he is the rightful winner -- a belief shared by the thousands of Iranians who have taken to the streets in protest in recent days.

Mousavi's statement posted on his website late Thursday effectively signalled he is ending his role in the street protests.

He said unfair restrictions were being imposed on him and complained that Ahmadinejad had been able to hold two post-election marches and a rally.

He also said authorities were attempting to isolate and discredit him -- but said he had agreed with a request from the Interior Ministry to seek permission for future protests one week ahead of time.

By Friday, however, Mousavi's website, Kalemeh, was coming up blank, and a spokesperson for Mousavi said the site was taking a day off, The Associated Press reports.

A police crackdown has resulted in violent clashes with protesters, and at least 17 people have been killed.

Journalists have been barred from covering the demonstrations, and many have been detained in the country.

Mousavi's position appears to be in flux. He vowed this week not to give up his fight, but also asked his supporters not to break the law.

Harsh punishment for riot leaders

Mousavi's website statement came ahead of remarks by Ayatollah Ahmed Khatami, a powerful Iranian cleric, who said during a Friday sermon that the leaders of the ongoing demonstrations should be punished "strongly and with cruelty."

He said the government should punish "leaders of protests, who were supported by the United States and Israel, strongly and with cruelty so it will be a lesson for everyone."

Khatami said those who disturbed the peace and destroyed public property were "at war with God," and said they should be "dealt with without mercy."

He also slammed foreign journalists for false reporting and slammed Britain, especially, for its behaviour.

"In this unrest, Britons have behaved very mischievously and it is fair to add the slogan of down with England to slogan of down with USA," he said. As he spoke during Friday prayers, his words were interrupted by worshippers chanting "Death to Israel."