An Iranian was shot dead during a banned opposition rally in Tehran, the semi-official Fars news agency reported, blaming opposition supporters for the shooting.
"One person was shot dead and several were wounded by seditionists (opposition supporters) who staged a rally in Tehran," Fars said, without giving further details.
Iranian security forces clashed with supporters of the opposition in the central city of Isfahan on Monday and arrested dozens of protesters at a banned rally backing uprisings in Egypt and Tunisia, a witness said.
"There were clashes between security forces and protesters in Isfahan and dozens of people were arrested," the witness told Reuters by telephone.
Iranian security forces fired tear gas to scatter thousands of people marching on a Tehran square. "There are thousands of people marching ... not chanting slogans ... Security forces fired tear gas to disperse them near Imam Hossein square," said the witness.
The march was a test of strength for the reformist opposition, which had not taken to the streets since Dec. 2009, when eight people were killed. But Iranian security forces are still unlikely to hesitate to use any means to stop protests.
Large numbers of police and security forces wearing riot gear were stationed around the main squares of the capital and traveling in pairs on motorbikes around the city. There were minor clashes at some points across the sprawling capital city of some 12 million people, witnesses said. Mobile telephone connections were down in the area of the protests.
"There were thousands of people walking towards Azadi Square. There were some scuffles. I saw smoke, but I am not sure if it was tear gas or not," said another witness.
The demonstrators marched down Enghelab and Azadi (Freedom) streets, leading to Azadi Square, a traditional rallying point for protests in central Tehran dominated by a huge white marble arch. Hundreds of marchers also gathered in the cities of Isfahan and Shiraz, witnesses said.
But security forces surrounded the houses of opposition leaders Mirhossein Mousavi and Mehdi Karroubi preventing them and Mousavi's wife, Zahra Rahnavard from joining the march, their websites said.
"Mirhossein Mousavi and Zahra Rahnavard are still trying to leave their house and join the protests... but security forces are preventing them. Security forces have even threatened Mousavi's guards to not allow them to leave the house by any means," the Mousavi's Kalame website said.
Mousavi and Karroubi took advantage of official Iranian backing for the huge street protests in Egypt and Tunisia to call their own demonstrations in solidarity, but authorities refused their request.
The opposition nevertheless renewed the call for the rally. Iranian authorities have warned the opposition to avoid creating a "security crisis" by reviving protests that erupted after the vote, the biggest unrest in Iran since the 1979 revolution.
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