An American airport worker described himself as "freaked out" when his iPod Nano caught fire in his pocket.

Danny Williams, of Douglasville in Georgia, was carrying his iPod in his trousers when he noticed a burning sensation and looked down to see flames shooting out of his pocket.

The Nano had caught fire, he said, and the results could have been a lot worse given his job at an airport.

"I am still kind of freaked out that after only a year and a half my iPod caught fire in my pocket," Williams told WSBTV.

"So I look down and I see flames coming up to my chest. If [the US Transportation Security Administration] had come by and seen me smoking, they could have thought I was a terrorist."

The cause of the fire is not yet known, but Apple has requested the unit back and has promised to replace it.

The Nano range uses lithium ion batteries that have been the subject of overheating problems in mobile phones, digital cameras and laptops.

Problems occur if the battery is contaminated with metal fragments that cause short circuits and ignite the battery's flammable fluids.