ATLANTA - At least one U.S. child has died and 19 others have needed surgery since 2003 after swallowing magnets used in toys, the government reported Thursday.

Most of those cases were believed to involve tiny but strong "rare earth" magnets that can link together in children's digestive tracts, squeezing and even perforating the intestines, the researchers said.

The magnets, made from neodymium iron boron or other compounds, have become common in the U.S. toy market in the past five years because they have become cheaper to produce, said Jonathan Midgett, the study's lead author and an engineering psychologist with the U.S. Consumer Product Safety Commission.

They are used in building sets, action figures and dolls.

"Most people who have never had them in their hands are shocked at how strong these tiny things are," Midgett said.

Kenny Sweet, a 20-month-old boy from Redmond, Wash., died in two days after he began complaining of stomach aches and vomiting. An autopsy found nine small magnets stacked together. They had caused a twisting of the bowel and a blood infection.

The magnets had come off a building set belonging to Kenny's 10-year-old brother, according to his family's lawyers. Mega Brands Inc. recalled 3.8 million Magnetix building sets, added warning labels and agreed to pay $13.5 million to settle lawsuits.

Last month, Mattel Inc. recalled more than 4 million Polly Pocket play sets, dolls with small magnets in their hands, feet, clothing and other accessories.

Last month, the U.S. Public Interest Research Group for the first time included the magnets on its annual holiday warning about dangerous toys.

Midgett said federal and industry officials hope to have a warning label ready within six months for toys containing magnets.