Dissidents are defying Iranian government attempts to silence them by distributing photos, videos and amateur reports of protests online.

In a rude awakening for the censors, young computer-literate opponents of the regime have taken to social networking websites to co-ordinate their protests and spread news.

One Facebook group called I Love Iran already has 65,000 members. On Monday one said: “The march in Tehran is still on. Any rumours that you hear are all propaganda from the government to make you stay away from the rally. Come to the rally at 4 and march for your freedom!”

In an attempt to curb such statements, access to Facebook was blocked last week, followed by bars on YouTube, anti-government websites and the micro-blogging site Twitter. As President Ahmadinejad proclaimed his “great victory” on Saturday, the mobile phone network stopped working and text messaging remains blocked.

However, the opposition were undeterred. Since Saturday an ad hoc network of volunteer internet users outside Iran has been creating proxy servers, or false IP (internet protocol) addresses to reroute online traffic and fox censorship software.

In an electronic game of cat and mouse, the creators of the proxy addresses post them online to alert Iranian dissidents. Censors leap to block each one as it appears, only to find that more have sprung up.

A group of overseas hackers is using a tactic traditionally employed by repressive regimes — a denial of service (DoS) attack — to block Iranian government sites. Using a free web application to create a deluge of clicks, by late Monday they had brought down the President’s personal website and that of a state broadcaster.

On Twitter, hundreds of updates tagged “iranelection” appeared each hour. A steady stream of photos and witness reports came from one Twitter user, persiankiwi. He sat at his computer in Tehran, as friends fed him information on the protests. “We honour and thank the people of Iran and especially the hackers,” he tweeted late on Monday. “Basij [the militia] have guns — we have brains.”

Times Recommends

• Both sides blame US for worsening relations
• Stieg Larsson: losing the plot over his cash
• Odd creature paralysed by incompatible parts