Dell has increased by 100,000 the number of laptop batteries it is recalling due to a potential fire hazard.

Dell said it received new information that caused it to increase its recall to 4.2 million batteries from 4.1 million. It urged customers to visit www.dellbatteryprogram.com and to recheck their batteries to see if they are affected. The site has received almost 200 million hits since the recall was first announced in August, Dell said.

The problems affect battery packs containing Sony-made Lithium Ion cells. Sony has discovered that metallic particles in the cells created during the manufacturing process could cause a short-circuit. That short-circuit could in turn result in a fire, depending on the way the laptop is designed.

While the affected notebooks from Dell and Apple Computer, which has recalled 1.8 million batteries, pose a potential fire hazard, Toshiba said its laptops are not in danger of catching fire. It said it was recalling the laptops voluntarily to ease concerns among customers.

Toshiba offered to replace 830,000 laptops, including some of its popular Satellite and Portege models.