Security tools designed for Windows Vista have failed to detect viruses in the circulation on the Internet.

According to Virus Bulletin specialists Microsoft's Live OneCare security tool was one of four products that failed independent tests conducted to see if they can detect contemporary viruses and malicious software. The tests showed that Live OneCare couldn't detect far more viruses than any other programme in question. The anti-virus efficiency tests can only be passed when an anti-virus tool can detect and stop 100% of the viruses used for the test. Microsoft's security focus Upon its launch on January 30th, Bill Gates claimed that Microsoft's Windows Vista operating system was "dramatically more secure" than any other software environment available on the market.

However, the tests performed at Virus Bulletin using viruses, bots, worms and trojan horses to compromise Vista's security showed that Live OneCare managed to spot 100% of the macro viruses but it missed some extremely aggressive and destructive viruses, polymorphic programs and file infectors.

Live OneCare managed to detect 99.91% of the known active viruses it was tested against, which generated a number of 37 malicious programs that are still potentially dangerous for the system integrity.

"The tests conducted in our secure labs were against the most significant viruses and worms affecting real-world users," said John Hawes, a technical consultant at Virus Bulletin.

"Although many improvements have been made, Vista cannot fend off today's malware without help from security products," he said.

Jo Wickremasinghe, Windows Live OneCare product manager, said in a statement: "We are looking closely at the methodology and results of the test to ensure that Windows Live OneCare performs better in future tests and, most importantly, as part of our ongoing work to continually enhance Windows Live OneCare to ensure the highest level of protection and service that we can provide our customers."