In this Feb. 15, 2006 file photo Chinese internet surfers play online games at an Internet cafe in Beijing, China. PC makers were given orders in May 2009 to implement new software by July that will block out violent and obscene material. (Associated Press)

Global business groups have made an unusual direct appeal to Chinese Premier Wen Jiabao to scrap an order for PC makers to supply controversial internet filtering software, citing security and privacy concerns.

Just days before the deadline to comply with China's order, the letter from 22 chambers of commerce and trade groups representing the world's major technology suppliers adds to pressure on Beijing to halt the plan following an official protest by Washington.

The order requires manufacturers to pre-install or supply Green Dam Youth Escort software with PCs made for sale in China beginning Wednesday.

"The Green Dam mandate raises significant questions of security, privacy, system reliability, the free flow of information and user choice," said the letter dated Friday, a copy of which was provided to The Associated Press. It appealed to Wen to "reconsider implementing the Green Dam requirements."

Such a direct appeal to Chinese leaders is highly unusual. Companies usually avoid commenting publicly on government policy for fear of retaliation.

The letter was signed by leaders of the American, European and Japanese chambers of commerce in China, the U.S. National Association of Manufacturers and trade groups representing the world's major technology suppliers.

Short timeline to implement

The filtering plan "seems to run counter to China's important goal of becoming a vibrant and dynamic information-based society," the letter said.

Chinese authorities say the Green Dam system is needed to block access to violent and obscene material.

But analysts who have reviewed the program say it also contains code to filter out material the government considers politically objectionable. The system also has been criticized by free-speech advocates and some of China's 298 million internet users.

PC makers received the order in May, giving them little time to test the software and work out how to comply. Manufacturers say they still are trying to obtain details of the plan.

A spokeswoman for China's Ministry of Commerce said she had not heard about the letter and declined to comment. A spokeswoman for the Ministry of Foreign Affairs said it was not in charge of the issue.

Top U.S. trade officials have called on Beijing to revoke the order requiring the filtering software, calling it a "serious barrier to trade" and citing security concerns. They said Beijing might have violated its World Trade Organization commitments by failing to give companies adequate advance notice and time to comment.

Internet monitoring enters the home

The conflict reflects the clash between the authoritarian government's efforts to control information and China's high-tech ambitions. China has assembled the world's most extensive system of internet monitoring and filtering, but the new software system would take the controls to a new level, placing monitoring technology inside the individual's computer.

China is important to PC makers such as Dell Inc., Hewlett-Packard Inc. and Taiwan's Acer Inc., both as a major manufacturing site and a fast-growing market. It accounts for up to 80 per cent of world production and sales.

The Green Dam plan has raised questions about whether the software, produced by a Chinese company, might cause technical problems, and how customers abroad will react to companies co-operating with Beijing's censorship.

Researchers at the University of Michigan who studied Green Dam say they found "serious security vulnerabilities due to programming errors" that could allow any website a user visits to take control of a PC.

A California company, Solid Oak Software of Santa Barbara, says parts of its own filtering software were used in Green Dam, raising questions about possible violations of intellectual property rights.

The Chinese manufacturer of the software has even received death threats.

Workers at Jinhui Computer System Engineering Co. have received more than 1,000 harassing phone calls this month, Zhang Chenmin, general manager of the company, told the official Xinhua News Agency.

Zhang was quoted Wednesday as saying one caller had even threatened to kill his wife and child.