China is weighing a ban on foreign cartoons in prime time, a rule that could hamstring multinational media companies striving to sell their lucrative programs and characters in the world's biggest TV market.

China's national television regulator proposed late last week to ban foreign-made animation programs from 5 to 9 p.m. The proposal is "still just being discussed," said Ge Chen, director of the cartoon department at the State Administration of Radio, Film and Television. "We are hearing opinions from all sides."

Chinese broadcasters said the notice is the government's way of signaling a change that it intends to make but that isn't yet practical for the country's nascent animation industry.

"This rule might take one year to be realized," said Chen Wen, director general of the Toonmax TV channel of Shanghai Media Group, China's second-largest media conglomerate. The government wants to attract more investment in domestic cartoons to improve their quality, Chen said.

China's media sector, which is still owned by the state, is among the last industries to be adapted to a market system. Last year, the regulatory agency announced it would allow foreign media companies to form joint ventures to produce content with Chinese companies, launching a flurry of applications for production partnerships.

But since the agency got a new director in December, industry executives said, it has been tapping the brakes with rulings such as the proposed cartoon ban.

Beijing has been on a cartoon-development crusade since 2000, when it mandated that at least 60 percent of cartoons aired on Chinese TV come from domestic sources. Most broadcasters -- other than the national China Central Television -- found that level difficult to meet, so last year the government announced plans to create 13 animation centers and offer tax incentives to local cartoon-production companies. Notice of the proposed prime-time ban came during a cartoon industry summit in the eastern city of Hangzhou.

Meanwhile, U.S. media companies such as Walt Disney Co. and Viacom Inc. have been battling for Chinese airtime and for public devotion to characters such as Mickey Mouse and SpongeBob SquarePants, which the companies hope to peddle everywhere from feature films to theme parks to T-shirts. Disney cartoons such as "Aladdin," "Tarzan" and "Pepper Ann" are featured, minus the Disney logo, on Beijing TV's "Dragon Club" program, which is syndicated in 44 Chinese cities, mostly during prime time.

In September, Disney will open a theme park in Hong Kong, targeted largely at tourists from mainland China, and hopes to open another in Shanghai after 2010.

In addition, Japanese cartoons are extremely popular on Chinese TV. For example, Japan's Sunrise Inc. distributes "Cho Majin Hero Wataru" to several broadcasters that show the anime program during prime time. The program tells the story of a schoolboy who travels to another dimension to save the world.

Disney spokeswoman Rita Chao said the company is studying the matter.

Viacom, Time Warner Inc., Sony Corp.'s Sony Pictures Entertainment and Sunrise declined to comment on the proposal.

Foreign media have little direct access to China's almost 400 million TV sets, with the exception of a handful of broadcasters such as the Xing Kong Wei Shi channel, a Chinese-language channel produced by Star Group, a unit of News Corp. that has been granted special access to broadcast to Guangdong province and other designated areas. Some media conglomerates and production companies sell limited blocks of programming to Chinese broadcasters.

Others enter into joint ventures with Chinese partners, such as the one between Viacom's Nickelodeon and Shanghai Media Group.

The proposed ban isn't likely to apply to cartoons produced by joint ventures, but cartoons that are designed overseas and produced and processed by Chinese animation companies still will be considered "foreign," Shanghai Media Group's Chen said.

A similar prime-time ban on foreign dramas went into effect in 2000 and has greatly aided the development of China's domestic drama-production industry, Chen said. Cartoons, however, are usually much more expensive to produce than live-action drama.

Kersten Zhang in Beijing and Ivy Zhang in Shanghai contributed to this report.