By Iain Mackenzie
Newsbeat Technology Reporter
The Japanese government has stepped in to look at the case of an "exploding" iPod.
Officials in the country have asked Apple to investigate the cause of the incident which came to light over the weekend.
A Nano owner reported their player overheating and shooting-out sparks while on charge.
It is believed the problem may relate to the device’s lithium ion battery.
Apple has not commented on the incident. However the company has warned that some iPods may become hotter than normal if kept in certain carry cases.
So far there are no plans to recall iPod Nanos in Japan.
If the battery is identified as the source of the explosion, it will be the latest in a long line of problems with lithium ion cells.
In 2006, Apple was forced to recall 1.8 million laptop batteries which had been made by Sony.
Around the same time, Dell recalled four million laptop batteries after one exploded in Japan.
Problems with lithium ion batteries have also affected mobile phones.
In August 2007 Nokia offered to replace 46 million batteries.
The company had received more than 100 reports of overheating in the BL-5C unit.
Despite their small size, lithium ion batteries can explode with great force.
A condition known as thermal runaway generates extremely high temperatures and often results in jets of flame bursting from affected batteries.