State television showed live footage of crowds carrying Iranian flags and pictures of Supreme Leader Ayatollah Ali Khamenei making their way to Azadi (freedom) Square in central Tehran, where the main gathering is held.


Neither side has shown much appetite for compromise in the eight months since the disputed June presidential vote, which the opposition says was rigged to secure Mahmoud Ahmadinejad´s re-election, and confrontations may intensify on Thursday.

The Islamic state is facing its worst domestic crisis in three decades as opposition supporters have rallied round reformists who lost to Ahmadinejad in the election.

Iran faces growing Western calls for targeted sanctions against it after Ahmadinejad ordered production of higher-grade uranium, stirring fears that Tehran aims to make nuclear bombs, not just fuel for civilian use as it says is the case.