Iranian riot police have clashed with opposition supporters in Tehran.
The opposition Jaras website said security forces fired warning shots in the air and tear gas to disperse protestors, and also attacked a building housing an Iranian news agency, ISNA, where it said some opposition backers had sought shelter.
If confirmed, the outbreak of clashes during a two-day major Shia Muslim ritual would underline escalating tension in Iran, six months after a disputed election plunged the country into turmoil.
Despite scores of arrests and security crackdowns, opposition protests have repeatedly flared since the June presidential poll, which the opposition says was rigged to secure hardline President Mahmoud Ahmadinejad's re-election.
