The Swiss Institute of Technology, Google and IBM conducted the study and found 600 million users had not updated their browsers. "Failure to apply patches promptly or missing them entirely is a recipe for disaster," the report said.

Cyber criminals are frequently using websites to attack users, it added.

The report authors recommended that a "best before" date, similar to the food industry, should be introduced to browsers, helping to educate users about the need to "refresh" their browser. Browsers are often "patched" by software providers to tackle recently discovered flaws and security holes.

Criminals exploit these holes with malicious code hidden in websites to hijack machines.

BBC News - July 8, 2008