WASHINGTON (AFP) - Microsoft has urged users of Internet Explorer to step up security measures following news of a vulnerability in the browser, while some security experts urged users to switch browsers.

Microsoft issued a security bulletin late Monday saying it was investigating reports of a vulnerability in Internet Explorer 6, 7, 8, and 9 which could allow hackers to take over a computer.

"Microsoft is aware of targeted attacks that attempt to exploit this vulnerability," it said, while urging its users to tighten security by adjusting settings on the Web browser and downloading a temporary software patch.

Some experts said, however, that switching browsers may be a better option.

"Today is a good day to think about switching browsers for a couple of weeks," said Rob VandenBrink on the blog of the SANS Internet Storm Center.

"There is code in the wild that exploits this (since September 14)."