Iranian protesters shout slogans as they gather to mourn Neda Agha-Soltan and other victims at Tehran's Behesht-e Zahra cemetery on Thursday. (Reuters)

Thousands of anti-government protesters were holding a memorial at a cemetery in Tehran on Thursday for the victims of post-election violence when police moved in.

Neda Agha-Soltan was shot dead during protests on June 20. (BBC)

Witnesses said the officers, in riot gear, fired tear gas and used batons to disperse the crowds. Opposition leader Mir Hossein Mousavi, who has decried the results of the June 12 election, was barred from speaking by police.

The protesters were gathered at the grave of Neda Agha-Soltan, who was shot during election demonstrations on June 20. Her dying moments were caught on video and became some of the iconic images of the upheaval, focusing worldwide attention on the unrest.

Freelance Iranian journalist Saeed Kamali Dehghan was at the protest when the violence erupted. He told the CBC's As It Happens about the chaotic scene.

Click here to listen to the audio.