China is tightening control over its online music and game industries, ordering distributors to submit all imported products for approval by official censors, the government said Tuesday.

The moves come amid official efforts to step up control over the Internet and other media, both to shield Chinese companies from competition and to suppress material deemed politically sensitive, violent or sexually graphic.

The music controls are meant to encourage growth of a "civilized and healthy" Internet and to protect Chinese companies that have lost market share to foreign rivals, the Culture Ministry said on its Web site.

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The rules apply to Web sites and mobile phone companies that distribute music, the ministry said.

It said distributors of Chinese music must register but won't be required to submit products for approval.

The rules also ban the establishment of foreign-financed music distributors, the ministry said.

In online games, distributors must obtain approval to release imported titles and must file monthly reports confirming that operators haven't added forbidden content, the official Xinhua News Agency said. It cited a notice by the Press and Publication Administration.

China has 23 million online game players, up from 13.8 million in 2003, according to Xinhua. It said revenues this year are expected to reach $850 million.

The crackdown was prompted by "a rash of problems with imported online games, some of which contain sensitive religious material or refer to territorial disputes," Xinhua said.

It said some were criticized as pornographic or too violent.

Regulators said distributors concealed the content of the games when applying for approval, and operators sometimes added improper content, Xinhua said.

It gave no details about the religious and territorial issues, but Beijing is sensitive to references to Islam and Taiwan, the self-ruled island that the mainland claims as its own territory.

Officials complain that the Internet and video games give Chinese children access to violent or sexual material and encourage them to waste time that should be spent on school work.

The government has restricted foreign content on television in recent years to protect Chinese production houses and to limit public exposure to political ideas and pop culture from abroad.

A regulator told The Financial Times in comments published last week that Beijing has imposed a moratorium on foreign investment in Chinese film and television production houses.

The government earlier imposed a similar temporary ban on new Chinese-foreign magazine joint ventures.