China banned discussion of "state secret information" on the Internet today in the latest in a recent series of attempts to control an information industry that is fast spinning out of the Communist Party's control.

The State Bureau of Secrecy issued a circular saying Internet users are prohibited from sending e-mail containing state secrets, discussing state secrets in Internet chat rooms or on bulletin boards. The circular also said content and service providers based in China must get a "security certification" before they can operate.

Under Chinese law, a state secret can be almost anything not officially released to the public, from crop reports to news about an earthquake. The government used this broad definition as a handy tool against against Chinese journalists, dissidents and other citizens.

The 20-article circular was the most recent in a spate of attempts by China's authorities to control the Web and limit its effect on China's closed political system. While China's government sees the Internet as a boon for the economy, authorities are also concerned that it will erode the Communist Party's ability to control information flowing in and out of China.

The ban appeared to be aimed particularly at Internet chat rooms, which have been used by a growing number of Chinese to criticize the government and exchange information about sensitive news. Government statistics show that Internet users in China are by and large young, single men who are better educated and wealthier than the average Chinese and tend to live in cities on the country's bustling eastern coast. The number who use the Internet jumped from 4 million to 8.9 million in the second half of last year alone, and they spent an average of 17 hours a week signed on.

Most recently, the chat rooms played a major role in publicizing corruption investigations in Fujian province that have implicated high-ranking military and political figures in Beijing and resulted in the arrests of scores of officials in the city of Xiamen.

"All organizations and individuals are forbidden from releasing, discussing or transferring state secret information on bulletin boards, chat rooms or in Internet news groups," reads Article 10 of the circular. Article 11 bans people from putting "state secrets" in e-mail. Article 8 orders that any site that "provides or releases information on the World Wide Web undergo security checks and approval."

Chinese Internet executives expressed concern that the regulations will stymie the meteoric rise of Internet use here and benefit overseas Chinese-language Web sites, which can escape China's Web regulations.

"This is all bad news for China," said Joe Sweeney, Asia research director for the Gartner Group, an Internet consulting firm. "It's sad because China's Internet is growing fast, but China is trying to rein in that growth."

The ruling was published in today's People's Daily, the official Communist Party newspaper. It was the fourth development this week with ominous ramifications for the Internet in China.

China recently issued regulations ordering all companies, including Western firms, to inform the government by the end of this month about encryption software they use to send confidential information over the Internet. As part of those regulations, Chinese software can only use data scrambling technology designed in China--a rule that could hobble electronic commerce here because many Chinese Internet merchants use encryption technology developed in the West.

Chinese officials have also hinted that local Internet firms that want to list their shares on foreign stock exchanges must obtain government approval.

Finally, China has moved to control content of Web sites. The Shanghai Daily reported today that the State Press and Publication Administration is crafting rules that would pose a "major challenge" for domestic Web sites by ensuring that they could only publish state-approved material.

Many of China's top Web sites give prominent space to reports on sports, entertainment and travel written by freelancers, who are usually not state-accredited journalists.

Internet entrepreneurs in China have reacted publicly with calm, in part because they do not want to irritate authorities and in part because the government has often issued tough restrictions only to back off later.

Paul Jin, an executive withSina.com, China's most popular Internet "portal," said his site is practicing self-censorship. "Even in the past when they didn't have rules on protection of state secrets, we've been careful," he said. "On politically sensitive matters, we wait until the government papers come out with their reports, then we put their versions on our site."

However, William Ding, president of Netease.com, China's second-most popular portal, said he wants the government to clarify the meaning of "state secrets." Ding said his staff often finds military or economic information put on the Internet by government departments that has not been released by the state-run media.

Sweeney said the encryption ruling is of most immediate concern because it demands that Western firms based here use Chinese technology, which could allow the government to unlock industrial secrets. "It's a serious threat for multinationals," he said. "It's industrial espionage."

Special correspondent Cindy Sui contributed to this report.