Fast food chain Burger King has announced it is recalling an estimated 25 million plastic balls containing Pokemon toys given away with children's meals after a 13-month-old girl was reportedly suffocated by one.

The baby was found dead in her crib in Sonora, California, on 11 December, with one half of a ball from a Pokemon toy over her face.

Pokemon characters - including Pikachu, Snorlax and Poliwhirl - were devised for a Nintendo video game and have become phenomenally popular with young children.

This November an animated film - "Pokemon: The First Movie," - was released in the US.

The name is short for "pocket monster" and children are encouraged to collect as many as possible with the catchphrase: Gotta catch 'em all!

Choke test

The balls - up to 7.5cm (three inches) in diameter - have been given away with children's meals over the past two months at Burger King outlets.

Ironically, the promotion had been extremely successful, with supplies running out 10 days into the campaign and new stocks being ordered.

The Pokeman toys and balls contained no warning and had met all US Consumer Product Safety Commission requirements and all international safety standards.

"They've passed all choke tests," said Charles Nicolas said.

"What's at issue is when the ball covers both the mouth and the nose."

Free fries

Burger King is now warning that the halves of the ball could become stuck on a child's face, covering the nose and mouth and causing a child aged under three to suffocate.

As well as the death in California, an 18-month old girl in Kansas was found with half the ball stuck on her face. It took her father two tries to remove the toy, but his daughter survived.

The company advised customers immediately to take the balls away from children aged under three.

The balls should either be thrown away or returned to any Burger King outlet where they can be exchanged for a free order of French fries.

The Pokemon toys themselves pose no danger and need not be returned, Burger King said.

The company has not revealed the cost of the recall.