Jimmy Wales, founder of online encyclopedia Wikipedia, is planning to build an online commercial search engine that would compete with Google and Yah

New York (dpa) - Computer security experts in California and Russia have found a series of flaws in Microsoft's Windows Vista, undercutting the software giant's claims that the new operating system is the company's most secure ever.

The most serious flaw involves a faulty piece of software underlying Internet Explorer 7 that could allow hackers to take over any computers that visit a rogue website set up to exploit the flaw.

Another security breach centres on code that allows users to upgrade their privileges on a computer, potentially allowing them to install unauthorized programmes.

The reports come just a month after Microsoft first released Vista to corporate customers. It is due to release the next generation operating system to consumers next month.

In a posting on its website, Microsoft said it was aware of the vulnerabilities but believed that there was only a low probability that they would be exploited.

"Currently we have not observed any public exploitation or attack activity regarding this issue," wrote Mike Reavey, operations manager of the Microsoft Security Response Centre. "While I know this is a vulnerability that impacts Windows Vista, I still have every confidence that Windows Vista is our most secure platform to date."