Hundreds of Iranians, wearing green accessories, shouted slogans in support of opposition leader Mir Hossein Mousavi, as they marched at the annual Quds Day rally in Tehran on Friday, witnesses said.
A witness told AFP that the crowds of young men and women, many wearing green wristbands, were shouting "Ya Hossein! Mir Hossein!" and also called for the release of political prisoners detained since the aftermath of the June 12 presidential election.
They also chanted "Don't be afraid, we are all together" and "Neither Gaza nor Lebanon, I will sacrifice myself for Iran," the witness said, adding the crowds were marching from the central Vali Asr square towards Tehran university.
Hardline President Mahmoud Ahmadinejad, whose re-election remains hotly contested by the opposition, was due to give a keynote address at the university later.
Green was the signature colour of Mousavi's election campaign.