"The toys on the dirty dozen list teach that violence is fun," said Daphne White, director of the Lion & Lamb Project, a non-profit group that has been compiling such a list since 1996.

At a news conference on Monday, White criticised toys like the "Kid Powered Roaring Hulk" and video games "Enter the Matrix", made by Infogrames Entertainment and "Terminator 3: Rise of the Machines", made by Atari Inc. The games are tied to movies intended for an older audience, and White called for regulation of the toy and entertainment industry.

A spokeswoman for a toy industry group told Reuters the appropriateness of toys was subjective.

"Playing with toys and imaginative play is an important part of childhood," said Julie Livingstone, director of marketing communications at the Toy Industry Association. "Parents need to be involved and aware of disturbing and overly aggressive behaviour."

Jeanne Funk, a clinical child psychologist at the University of Toledo in Ohio who has studied the effect of video games, said children whose favourite games tended to be violent had less empathy for other people.

Video games do not cause children to be less empathetic, but Funk said, "There's no reason to believe that playing violent video games would improve empathy."