PhD engineering student Javad Forughi said it was important to raise awareness of the situation.

"We need support from other countries," he said.

"We don't have the power - we need international support."

Frightened for his brother, sister and parents in Iran, Mr Forughi has had trouble sleeping, and he was relying on social-networking site Twitter for updates from them.

Mr Forughi said he was hearing many reports of violence from his family and was increasingly concerned for their safety.

Another student, too afraid of repercussions in Iran to be named, said he was finding it harder to contact family, and Twitter was his main source of information.

Dr Jason Wilson, a lecturer in digital communications at the university, said while it was more likely people were communicating via mobiles and word of mouth inside Iran, Twitter was becoming increasingly important.

"It's enabling people to maintain contact with loved ones in Iran and the rest of us to follow events and show solidarity," he said.

Dr Wilson said the growing use of Twitter throughout the crisis demonstrates the social potential of these sites.

"It's shown us you're able to galvanise people on social issues.

"People who have expertise in this area, such as academics and journalists, are just as likely to be on Twitter, so people are being informed."

However, Dr Wilson said there were downsides to information being shared via the mini-blogging service.

"People don't have that moment's thought between seeing a link and sending it on.

"It's all very well to re-tweet something and pass it on if it's trivial, but now people are realising you have to be careful.

"There are consequences (such as safety issues for people inside Iran) of passing on this information."

Dr Wilson said users also needed to treat information critically, questioning whether sources were reliable and their motives for passing on information.