Microsoft is facing a court case in China over its moves to stop computer users stealing its software.

In August Microsoft introduced a new feature to its Windows Genuine Advantage (WGA) software that turned the wallpaper of computers using a pirated version of Windows XP Pro black every 60 minutes and displayed a message that the software was pirated.

The feature has now been rolled out to Chinese users and has caused a storm, and a legal challenge from Beijing lawyer Dong Zhengwei, according to Chinese state media.

The complaint describes Microsoft as "the biggest hacker in China with its intrusion into users' computer systems without their agreement or any judicial authority".

"Microsoft's measure will cause serious functional damage to users' computers and, according to China's Criminal Law, the company can stand accused of breaching and hacking into [the] computer systems of Chinese [users]," it added.

Chen Chong, director of the China Software Industry Association (CSIA), said: "I respect the right of Microsoft to protect its intellectual property but it is taking on the wrong target with wrong measures.

"[Microsoft's move] is very bad and the whole industry in China must take it seriously."

The CSIA is to take action against Microsoft over the WGA software, which is downloaded by Windows computers when they install updates.

China has one of the highest piracy rates in the world, with an estimated 82 per cent of systems running pirated code, according to the Business Software Alliance.

Fang Xingdong, an internet analyst and president of research company Chinalabs.com, predicted more problems ahead for Microsoft and the WGA programme.

"Microsoft is manipulating our computers through the WGA and it will affect our use of computers," he said.

"The company should stop the action immediately and do some constructive things, such as lowering the price of its software and changing its business models."