Users are being told to avoid using Internet Explorer until Microsoft patches a serious security hole in it.

The loophole is being exploited to open a backdoor on a PC that could let criminals take control of a machine.

The threat of infection is so high because the code created to exploit the loophole has somehow been placed on many popular websites.

Experts say the list of compromised sites involves banks, auction and price comparison firms and is growing fast.

Serious problem

The net watchdog, the US Computer Emergency Reponse Center, and the net security monitor, the Internet Storm Center, have both issued warnings about the combined threat of compromised websites and browser loophole.

Cert said: "Users should be aware that any website, even those that may be trusted by the user, may be affected by this activity and thus contain potentially malicious code."

In its round-up of the threat the Internet Storm Center bluntly stated that users should if possible "use a browser other then MS Internet Explorer until the current vulnerabilities in MSIE are patched."