A hacking war has broken out between Swedish and Turkish hackers after several newspapers in Sweden published a caricature of the prophet Muhammed. Around five thousand websites have been affected, including those of Linköping Cathedral and Gothenburg Council, according to the English-language Swedish newspaper The Local.

Swedish hackers are reported to have retaliated by breaking into Turkish forums and posting pornographic images of Muhammad and Kemal Atatürk, founder of the modern Turkish state.

Stefan B Grinneby, head of the Swedish IT Incident Centre (SITIC), has asked local hackers to exercise restraint to prevent an escalation.

Inevitably security firms are using the battle as a dire warning for companies to beef up their protection. Geoff Sweeney, chief technology officer of Tier-3 said companies can learn a lot from the methodology of the hackers, and claimed "more advanced" measures like behavioural analysis offered better protection because it provided a safety net against unknown as well as known threats.