BEIJING — China imposed broad new restrictions Sunday on the distribution of foreign news in the country, beefing up state regulations on the news media.

Under new rules that were said to take effect immediately, the state-run New China News Agency said it would become the de facto gatekeeper for foreign news reports, photographs and graphics entering China. The agency announced in its own dispatch that it would censor content that "endangers national security."

If enforced as drafted, the regulations could have a major impact on news agencies like The Associated Press, Reuters and Bloomberg News that sell news-related products to a wide range of Chinese clients.

More generally, the step appears intended to further restrict the information that news media in China, including news-oriented Web sites and financial, cultural and sports publications, can receive and convey to viewers or subscribers. Many such media outlets have skirted censorship procedures that old-line media must follow in China, a one-party state.

Party leaders have been alarmed by the increasing assertiveness of the domestic and the foreign news media. After a period of relative openness, officials now seem determined to make sure that the Chinese public does not have easy access to information that could provoke popular discontent or weaken the governing party's grip on power.

President Hu Jintao has intensified a crackdown on all kinds of news media in recent months, arresting and harassing journalists, tightening regulation of Web sites and online forums, hiring tens of thousands of people to screen and block Web content deemed offensive, and firing editors of state-run publications that resist official controls.

The New China News Agency has long played a dual role in China's media world. It acts both as the official distributor of state news and information, selling its products much as any Western news agencies would do. But it also regulates outside news agencies, a power that Western news providers say it seeks to use to enhance its own bottom line.

A decade ago, the New China News Agency sought to take control of the lucrative business of providing live news and data feeds to banks and financial firms in China, determining pricing, policing content and collecting the revenue.

The industry, dominated by big Western agencies like Reuters and Bloomberg, successfully fought those restrictions. They have continued to market their products directly to brokers and traders in China rather than providing all services through the New China News Agency.