Iran students again defy authorities via Twitter

By Channel 4 News

Police have clashed with crowds of people in Iran as demonstrators use a national "student day" to renew their challenge to the government, telling the world via Twitter.

It is six months since the disputed presidential election in which President Mahmoud Ahmadinejad secured another term in office, despite a groundswell of support for his rival Mirhossein Mousavi.

The June vote sparked Iran's worst unrest since the Islamic revolution three decades ago and exposed deep divisions in the establishment. Authorities deny allegations of vote-rigging.

The state rally in Tehran marks the killing of three students under the former Shah. Witnesses say police have fired teargas and battled with protesters in various squares in the city.

As with the controversial election in the summer, the internet, mobile phones and Twitter have been playing a large part in the way demonstrators are communicating - with each other and the outside world.

"Students of Tehran University are being prevented by security forces from leaving the university ... They wanted to join demonstrators at other universities," said one website run by students.

Internet connections have been very slow as the Iranian authorities attempt to curb online communication.

But protesters have been able to post important information and images to the Twitter social network site using #16Azar and #iranelection hashtags to help followers keep track of events. One announcement read: "Due to heavy security outside Tehran University, gatherings will now take place outside the following six universities."

Many photos from rallies have been uploaded and videos sent to YouTube. In June, attempts by President Ahmadinejad to hush up the angry protests were thwarted when a global campaign took off on Twitter. Millions of the site's users around the world turned their profile pictures green as a mark of solidarity.

Green is the colour chosen by the opposition movement to represent their plight. The Prophet Mohammed is said to have worn a green cloak and turban.

Iran's Revolutionary Guards and their allied Basij militia warned the opposition not to use today to revive protests against the June vote, but this appears to have backfired.