Japan's trade ministry has ordered Apple Inc's Japan unit to state on its website that users who are concerned about their iPod nano portable music player catching fire can receive a replacement battery.

The ministry ordered Apple to publish an easy to understand statement online explaining how users of the devices -- responsible for four cases of minor burns in Japan -- can receive replacement batteries and obtain advice, a spokesman for the ministry said on Friday.

The Japan arm of Apple, the world's biggest technology company by market value, came under scrutiny last week when it was ordered to explain 27 incidents of overheating in some models of its first-generation iPod nano portable music players.

Apple said last week that the issue had been traced to a single battery supplier.

The company said on Friday that safety is the highest priority.

We've worked closely with METI to make sure first-generation iPod nano customers who are concerned with their battery have the latest information, said Apple spokesman Tom Neumayr.

(Reporting by Benjamin Shatil and Gabriel Madway, editing by Matthew Lewis)

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