WASHINGTON -- Consumer and parent advocacy groups accused entertainment industry executives Wednesday of not doing enough to shield children from excessive violence, sex and other inappropriate fare.

Some of the groups at a Capitol Hill forum called for government intervention, but executives from the film, music and video game industries said self-regulation is working.

Jack Valenti, president of the Motion Picture Association of America, defended the film industry's voluntary movie rating system of G, PG, PG-13, R and NC-17.

"One of the reasons why the movie rating system has lasted is its simplicity," said Valenti. "You give away things with simplicity, but you also entice people to use them."

But Nell Minow of the group Common Sense Media said the ratings can be too simplistic and lead to mislabeled movies that expose children to grisly images.

"We have a PG-rated Star Wars where a child picks up a helmet and finds his father's severed head in it, but because you don't see any blood ... it's still a PG," Minow said.

The video game industry came in for harsh criticism during the daylong conference sponsored by the Federal Trade Commission, which recently released a study suggesting that teens have little trouble buying violent video games or CDs with parental warnings.

The study found that nearly 70 percent of teenage shoppers aged 13 to 16 could buy M-rated -- for mature -- video games meant for people 17 and older.

Consumer advocates also showed footage from violent video games that the groups complain are being marketed to youngsters.

In one clip from the video game series "Grand Theft Auto," a man is heard having sex with a woman, then beating her and later blowing away police officers. The game is marketed with an "M" rating, but the consumer and parental groups argued it should be an "AO," for "Adults Only."

Patricia Vance with the Entertainment Software Rating Board said warning labels are prominently displayed on videos, which also carry descriptions of content. She said parents are the key to keeping children from getting their hands on videos intended for adults eyes only.

But Daphne White of The Lion & Lamb Project, which aims to stop the marketing of violence to children, advocated stronger involvement by the government.

"Everyone is hiding behind this cloak of the First Amendment," said White, who wants to see better labeling on music, movies, TV programs and video games.

"I think there has to be some regulation of marketing of these products," she said.

Common Sense Media's Minow said government should have a more limited role. Her group instead called for a single, uniform rating system for all media products that would be overseen by an independent group of parents, educators and child development experts.

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On the Net:

Motion Picture Association of America: http://www.mpaa.org

Entertainment Software Rating Board: http://www.esrb.org