New anti-government demonstrations in the Iranian capital Tehran have led to fierce confrontations throughout the city between opposition supporters and the police.

Various sources report that demonstrators have come under fire and that there have been casualties. Riot police have also been using truncheons and tear gas. The Russian and British embassies have been cordoned off by hundreds of police as a precautionary measure.

The opponents of President Mahmoud Ahmadinejad have been chanting the slogan, "Death to dictators". Opposition leader Mehdi Karoubi has also taken part in the protests but was forced to make a speedy exit when attacked by hardline pro-government supporters. Anti-government protests have also been staged in other Iranian cities.

Earlier today, the opposition hijacked a major anti-United States demonstration and staged a protest against the disputed outcome of June's presidential election in Iran. They say President Ahmadinejad won thanks to widespread electoral fraud.

Today is the 30th anniversary of the storming of the US embassy by radical Iranian students. They took 52 people hostage who were only set free after 444 days. US President Barack Obama has marked the anniversary by calling on Iran to look to the future and not the past.

photo: anti-government protest in Tehran (EPA)