China has told US software giant Microsoft to reconsider controversial new anti-piracy tools that cause computer screens to turn black if a pirated program is identified, state media reported.

"Whether the 'black-out' method should be adopted is open to question," said Yan Xiaohong, vice director of the National Copyright Administration, according to a report carried by Xinhua news agency late Monday.

"Measures for safeguarding (intellectual property) rights also need to be appropriate. We've paid great attention to the 'black-out' issue."

Yan was speaking after Microsoft rolled out its Windows Genuine Advantage programme, which turns computer desktops black every hour if the installed Windows XP operating system fails an authenticity validation test.

The move has caused an outcry among Chinese users, who have branded it as "unfair" monopoly tactics designed to make average Chinese pay prices that are far too high for average incomes, earlier state media reports said.

Yan said that the strategy of using a unified global price for some of Microsoft products was questionable, arguing the company's price policies "should fit the Chinese situation", according to Xinhua.

"The company adopted unified prices in the past without considering the income gap between developed and developing countries," he said.

However, Microsoft defended the "black-screen" action as a legal move meant to protect its copyright, adding it has in recent years set certain product prices at competitive levels that Chinese users can afford.

"Building a market environment that respects intellectual property rights is critical to the development of the entire software industry and of the knowledge economy in China," the company said in a statement sent to AFP.

"Microsoft works to ensure its operations are in compliance with laws and regulations on a worldwide basis including in China. Microsoft will continue conducting our operations in compliance with laws and regulations in China."

In 2007, 82 percent of all personal computer software sold in China was pirated, unchanged from 2006, but down from 92 percent in 2003, according to the Business Software Alliance, an anti-piracy organisation.

While the piracy rate is on a long-term declining trend, the amount of money that the software industry misses out on is increasing rapidly.

Losses caused by Chinese software piracy amounted to 6.7 billion dollars in 2007, up from 5.4 billion dollars in 2006 and 3.8 billion dollars in 2003, figures from the organisation showed.