Fujitsu Ltd. said Friday it will recall an additional 51,000 Sony-made lithium-ion batteries worldwide for its laptop personal computers for possible overheating problems, while Sharp said it will recall about 28,000 Sony batteries.

Mamoru Wakamatsu, a Sharp spokesman, said the batteries were installed in its laptops for the Japanese market, under its PC-MR series of Mebius.

The latest announcements bring the number of such batteries subject to voluntary recall and replacement to about 7.7 million worldwide.

Fujitsu and Sharp said they have not received any reports of overheating problems with the batteries.

Earlier this month, Fujitsu said it would recall 287,000 lithium-ion batteries made by Sony.

Of the 338,000 Fujitsu batteries, 78,000 were sold on the Japanese market and the rest overseas, according to Fujitsu spokesman Toshiaki Koike.

Fujitsu said it will offer free replacements starting Oct. 20 in Japan.

As for overseas models, Fujitsu said it will start the recall program, country by country, in late October. It said it would provide details later.

Since August, Dell Inc., Apple Computer Inc., Lenovo Group Ltd., IBM Corp., Toshiba Corp., Hitachi Ltd., Fujitsu and Sharp have decided to recall Sony-made lithium-ion batteries.