Panasonic is recalling several thousand laptop battery packs because mechanical problems with the pack's latch could lead to overheating of the battery.

The recall applies to around 6,000 battery packs that were shipped with its CF-W4G Let's Note W4 laptop computers in April and May of 2005, the company said today. The recall applies only to machines shipped in Japan.

The problems arise occasionally if the owner drops the machine or sets it down on a table very roughly, according to Akira Kadota, a spokesman for Panasonic in Tokyo. On such occasions the small spring in the latch can penetrate the battery pack and cause a short circuit that leads to overheating, he said. Panasonic has documented two cases to date of this happening with the battery packs under recall.

"This is very different from the Sony case," he said, referring to recent recalls by Dell and Apple of almost six million battery packs containing Sony-made cells. Sony said the presence of metallic particles inside the battery meant there is a chance that the cells could overheat and catch fire under certain circumstances.

The cells in the batteries under recall were not made by Sony or Panasonic, said Kadota. He wouldn't name the battery maker.