Following Lenovo's announcement yesterday that it is recalling 208,000 ThinkPad batteries used in its notebook computers, battery maker Sanyo today defended its own products.

Sanyo Electric said the battery problem resulted from strong external impact to the battery and that there was not a problem with the "batteries themselves".

The recall affects Sanyo's 9-cell Lithium-ion extended-life battery pack. "While the pack fully satisfied specifications and internal testing standards, these incidents occurred due to a strong external impact to the battery pack of a specific notebook PC model from a certain angle," Sanyo said in a statement .

"The incidents were not triggered by the battery cells themselves."

Sanyo spokesman Akihiko Oiwa said the company was still assessing how much the recall will cost and could not comment on the matter.

Lenovo warned that the batteries pose a fire hazard to users following reports of overheating. The recall was the second for Lenovo in the past six months; the company withdrew half a million Sony batteries last September.

Sanyo said it is supporting Lenovo's recall and has already started "working together with Lenovo putting the first priority on consumer safety".