Computer experts have warned that a "super" virus has attacked more than 6 million personal computers and almost 1,000 corporate computers in China.

The Stuxnet cyberworm can break into computers and steal private information, especially from industrial firms, sending it back to a server in the United States, said Wang Zhantao, an engineer at the Beijing-based Rising International Software Co. Ltd., a leading antivirus service producer in China.

The super virus made use of a bug in Siemens auto-control systems used in industrial manufacturing to skip the security check, Wang said.

The virus can copy itself and spread via U-disk in the network of a company and government.

"Hackers may take control of a company's machinery run under computers infected by Stuxnet, and give dangerous orders causing serious damage," he said.

The company has developed software to kill the virus, which can be downloaded for free from the company's official website, he added.

China had 420 million Internet users as of June, according to statistics from China Internet Network Information Center.