June 27 (Bloomberg) -- The American Medical Association called for research on the risk of addiction for the 90 percent of U.S. children who play video games, many of them violent.

The video game industry's ratings system, established in 1994, should also be reviewed, the AMA, the nation's largest physicians' group, said today in a statement at its annual meeting in Chicago.

The consequences of constant exposure to the games aren't fully understood, the AMA said. Research shows the games improve hand-eye coordination, while other studies suggest the violence in some of them may cause harm.

``While more study is needed on the addictive potential of video games, the AMA remains concerned about the behavioral, health and societal effects of video-game and Internet overuse,'' said Ronald Davis, the group's president. ``We urge parents to closely monitor their children's use of video games and the Internet.''

More accurate ratings would help parents determine whether specific games are appropriate for children, the AMA said.

Machines used to play video games are made by companies such as Nintendo Co. and Sony Corp., both of Japan, and Microsoft Corp. of Redmond, Washington. The games are made by companies including New York-based Take-Two Interactive Software, known for its violent ``Grand Theft Auto'' series. Take-Two suspended release of its new game, ``Manhunt 2,'' this month after it was banned in the U.K. and given an adults-only rating in the U.S.

Software Ratings Group

The Entertainment Software Rating Board, the voluntary, nonprofit agency set up by the industry, rates virtually all video games sold in the U.S. and Canada. The system's effectiveness has been confirmed by the Federal Trade Commission and the Kaiser Family Foundation, the ratings group said.

``While we agree with the AMA that parents should play an active role in determining which games their children play, their call for a review of the ESRB rating system seems to disregard the fact that the vast majority of parents are satisfied with ESRB ratings,'' said Patricia Vance, president of the ratings group, in a statement.

Separately, the AMA said the State Children's Health Insurance Program should be reauthorized and expanded by U.S. lawmakers.

Congress is reviewing the program, which provides coverage to more than 6 million low-income children and is set to expire in September. Democrats are seeking to expand the program beyond the funding proposed by President George W. Bush.

``Physicians see the benefits of the Schip program firsthand: parents who work hard, but aren't able to afford health insurance, are able to get their children the care they need,'' said Samantha Rosman, a pediatrician and AMA board member.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

Last Updated: June 27, 2007 18:26 EDT