Car manufacturers in the UK have become the latest victims of computer hackers who have defaced the websites of four of them in the last two days.

UK sites belonging to Ford, ChryslerJeep, Fiat and Mitsubishi were all defaced by hacker group Prime Suspectz. Fiat and Mitsubishi's sites still displayed the hacker's messages at lunchtime today.

The defacements were carried out by the same group that yesterday attacked Microsoft's New Zealand site, which had still not been restored today more than 24 hours after the incident. Compaq's Polish website was also defaced last night by Prime Suspectz.

The hackers posted a message including the text "security wuz broke'n! but they can believe because the truth iz that prime suspectz wuz here".

All the attacks exploited known gaps in Microsoft's Internet Information Server (IIS), for which patches have been available for many months.

Paul Rogers, a network security analyst at MIS, said: "I'm really surprised that security policies clearly haven't been followed, particularly in Mitsubishi's case, which hosts its website in-house. They all really should review their policies."

"At the end of the day you can manage the risk and if you don't make the effort you will slip up. Security can never be 100 per cent but you can secure your site against known risks because the patches are available," he added.

"Its all about customer perception and if they see sites are being defaced easily it implies that these sites are less secure."