Iran revolts as police arrest dozens

The rallies amounted to a test of strength for the reformist opposition, which had not taken to the streets since December 2009, when eight people were killed.

"Witnesses say in some parts of Tehran security forces arrested dozens of protesters," opposition leader Mirhossein Mousavi's Kaleme website reported.

Security forces fired teargas to scatter thousands of people marching towards a Tehran square, a witness said. There were also clashes between police and demonstrators, and dozens of arrests, in the city of Isfahan, another witness told Reuters.

"Death to the dictator," some of the Tehran protesters chanted, though other demonstrators marched in silence. Some chants drew comparisons between the Iranian leadership and the autocrats deposed in recent weeks in Tunis and Cairo.

Amnesty International condemned the authorities' reaction: "Iranians have a right to gather to peacefully express their support for the people of Egypt and Tunisia," it said.

Iranian Supreme Leader Ayatollah Ali Khamenei has called the uprisings in Egypt and Tunisia against secular, Western-allied rulers an "Islamic awakening," akin to the 1979 revolution that overthrew the U.S.-backed shah in Iran.

But the opposition see events in Tunisia and Egypt as being like their own protests after the June 2009 election which they say was rigged in favour of President Mahmoud Ahmadinejad.