PhotoApple is recalling some of the first-generation iPod Nanos, warning there’s a slight risk the battery could overheat and catch fire.

“Apple has determined that, in very rare cases, the battery in the iPod nano (1st generation) may overheat and pose a safety risk," the company said. "Affected iPod Nanos were sold between September 2005 and December 2006. This issue has been traced to a single battery supplier that produced batteries with a manufacturing defect. While the possibility of an incident is rare, the likelihood increases as the battery ages.”

Apple provided a form on its Web site where iPod owners can check their Nano serial number and determine if their model is among those included in the recall, which Apple is referring to as a "replacement program."

Customers whose serial numbers match those included in the recall will get a free first-generation replacement unit.

Apple so far is not saying how many units are potentially affected.  It says the affected iPod nanos were sold between September 2005 and December 2006.

This issue has been traced to a single battery supplier that produced batteries with a manufacturing defect. While the possibility of an incident is rare, the likelihood increases as the battery ages, the company said.

Customers should stop using their first-generation Nanos until they determine whether it is one of the units being recalled.