As the first impacts of the Ganda worm, which plays on curiosity for news about the Iraq invasion, begin to be felt, online observers have also noted a surge of anti-war hacking.

In the 48 hours before the invasion of Iraq just over 200 websites were attacked and defaced, but in the following 24 hours around 1,000 were targeted, predominately by anti-war protestors.

Sites successfully breached include those belonging to the US Navy and US National Centre for Agricultural Utilization Research.

"This is not hacking for hacking's sake but hacking with a political motive," said Jason Holloway, UK general manager at F-Secure, which has been monitoring such attacks.

"There's a range of hackers and activists doing this. There's a few anti-Iraq or anti-US attacks but the overwhelming majority are simply anti-war; that seems to be the strongest message."

Most of the activity has relied on basic automated hacking tools relying on scripts, which elite hackers usually refer to as "script kiddies".

The FBI has already issued a warning to US citizens that anyone, even pro-US or "patriot" hackers, will be prosecuted to the fullest extent of the law.

The Ganda worm spread using war as a way to influence the unwary to activate its payload, and similar viruses have already attempted to use the Iraq conflict for their own ends.

The Lioten or Iraq_Oil worm had limited impact when it was released in December last year, as did Prune last week, which spread by purporting to come from the US military.

Ganda, which appears to have originated in Sweden, has so far failed to have a major impact outside its home country.

"It helps that it's a bilingual [English and Swedish] virus but there's more to it than that," said Graham Cluley, senior technology consultant for Sophos.

"The Swedes seem to have taken the view that they only had to be worried about viruses in emails written in English. This has come as rather a rude shock.

"The virus's Swedish writer, Uncle Roger, may be having his collar felt forthwith. There are a lot of angry Swedes out there."