The Iranian opposition has launched a cyber-attack against the major pro-Ahmadinejad Iranian websites, amid accusations that the recent election in which president Ahmadinejad was re-elected was fixed.
The cyber campaign appears to have been organised on Twitter, despite the social networking site apparently being banned in the country.
The attackers have used methods common to political protest, including denial of service attack tools and PHP script.
The latest reports suggest both sides of the political fight are engaging in cyber warfare.
Rik Ferguson, a senior security advisor at Trend Micro, said, "It seems to be happening from both sides of the political fence. They are using IP blocking, denial of service and hacking tools."
The attacks included sites belonging to Iranian news agencies, president Mahmoud Ahmadinejad's site president.ir, and Iran's supreme leader Ayatollah Ali Khamenei. The sites went off-line after protesters targeted them with a number of tools, but some appear to be working now.