Beijing Evening News reported on Wednesday that "several tens of thousands of computers" in China have already been infected, while 2,000 intranet systems had collapsed.

Individual computer owners and small businesses appear to be bearing the brunt of the attack, experts said.

"If the computer users have not downloaded Windows special anti-virus software programs, their computers could become infected by this virus," an official at the National Computer Emergency Response Center said. "We have had about 10,000 phone calls and e-mails from computer users around the country, including government institutions, enterprises and individuals and this is what we are telling them."