The directive aims to block users from specific sites and content, including pornography, according to Jinhui Computer Systems Engineering, the software maker. But foreign industry officials who viewed the software told The Wall Street Journal the move will give the Chinese government even more control over what users are viewing on the Internet.

China has the world's largest Internet population with 179 million users, or 18 percent, as of December, according to comScore.

Tightening the Squeeze

China is tightening its grip on lewd content available to those 179 million users. Earlier this year, the China Internet Illegal Information Reporting Center (CIIRC) cited several Web sites for having a large amount of lewd content.

China has shut out up to 1,507 Web sites since its CIIRC antiporn campaign launched on Jan. 5. More than 70 Web sites, including Sina, MSN China, and search engines Google and Baidu, have been given warnings to remove pornography, according to the official portal of the People's Republic of China.

The squeeze on content isn't a surprise. China already controls an Internet filtering system known as the Great Firewall, which blocks access to sites that have anything from pornography to political content.

The directive is a very unfortunate development, according to Marc Rotenberg, executive director of the Electronic Privacy Information Center in Washington, D.C.

"The problem with Internet filters has always been that a voluntary approach could be made mandatory," he said. "EPIC warned about this shortly after the Supreme Court decision back in 1997 that struck down the Communications Decency Act."

"It had already happened in the U.S. with respect to computers in schools and libraries," Rotenberg added. "Now China is going farther."

A Tight Deadline

In March, China blocked YouTube after a video showed security forces beating Tibetans. Wikipedia was blocked for a while for information that was on its Web site. And most recently, Twitter, Flickr, Bing, Hotmail.com, and live.com were also reportedly blocked. Opponents of Chinese control over content say the recent blocks are the regime's way of controlling content on the anniversary of the Tiananmen Square massacre on June 4, 1989.

Blocking pornography isn't an issue for manufacturers, but the looming deadline of July 1 is a challenge for most companies, including Dell , Hewlett-Packard, and others who sell PCs in China. China-based Lenovo, which manufactures IBM laptops, has the largest market share in China.

Companies will have to ramp up efforts to include the blocking software in production lines in order to comply with the new directive.

Reader Feedback

One of our readers in China wrote to us, indicating that while "a slew of sites are blocked," not all of the sites mentioned above are indeed being blocked -- despite the fact that the U.S. media is widely reporting the blockage.

This reader indicated that he can still reach Twitter.com, Hotmail.com, Flickr.com, and Live.com without any trouble. YouTube, he said, is the only site that is unreachable to him, at least in his daily surfing of the Net.