Insurance companies are at grave risk from cyber attacks and could see their websites defaced with pro or anti-US propaganda following the September 11 events.

Technology consultant Ross Hall of Garol said it was likely that insurance companies could be the victim of "hacktivism", as insurers are already financially exposed after the terrorist attacks and are therefore an easy target.

There have been several high-profile hacking cases in recent weeks. Lloyd's of London and banks Barclays and Lloyds TSB have all had their websites defaced.

Cyber criminals can install "Trojan horses", systems that allow a back door for hackers to enter companies' databases and websites.

"Information technology departments need to have an extra level of vigilance, auditing systems and checking for back doors," said Hall.

"Every time there is a political situation, there is a spate of hackers who want to make their mark."