One of the websites involved in web hacking activity in China belongs to a Chinese governmental office, according to security vendor Finjan.

The firm has monitored how users' PCs are being infected by data-stealing Trojans distributed from China.

Some of the attacks are highly sophisticated, said Yuval Ben-Itzhak, chief technology officer of Finjan.

"The development is disturbing for governments, enterprises and individuals alike - signature-based defence technologies like anti-virus and URL Filtering are limited against them," he said.

On Friday, Computing revealed that MI5 spy chief Jonathan Evans' warning to UK businesses of China's People's Liberation Army's concerted campaign of cyber espionage.

And a recent report found more than 120 countries from all over the world actively engaged in either cyber warfare or high-tech espionage against other states.