Toshiba, Fujitsu and Dell recalled more Sony-made laptop batteries Friday, swelling the number of units involved in the massive global recall to more than seven million.

Early Friday, Sony Corp. formally asked manufacturers using its problem batteries to carry out a recall.

Sony has said the batteries could pose a risk of fire in rare cases when microscopic metal particles generated during manufacturing come into contact with other parts of the battery cell, leading to a short circuit.

Typically a battery pack will power off when there is a short circuit, but on occasion the battery can catch fire.

As a result of the request, Toshiba Corp. is recalling 830,000 Sony-manufactured batteries for its notebook computers. Dell Inc. boosted its own recall by 100,000 for a total of 4.2 million.

Fujitsu Ltd. is recalling an undisclosed number of Sony batteries that are used in 19 of its laptop models, according to Fujitsu spokesman Masao Sakamoto.

Toshiba spokesman Keisuke Omori said Toshiba had not found any cases in which its laptops were at risk of catching fire, "But we wanted to assure and satisfy our customers."

Toshiba issued a worldwide recall on Sept. 19 involving 340,000 laptop computer batteries manufactured by Sony, including 9,000 sold in Canada, but it was related to a separate technical issue that prevented some batteries from charging properly.

Friday's 830,000-unit recall involves Toshiba's Dynabook, Qosmio, Satellite Portege and Tecra models, but regional breakdowns and dates of manufacturing weren't immediately available, Omori said.

Dell said the addition of 100,000 units to its existing recall was made as a result of new information received about the affected battery packs containing cells manufactured by Sony. In August, Dell recalled 4.1 million laptop batteries, and said in a statement that the recall would affect approximately 95,000 battery packs sold in Canada.

A battery of recall decisions

Late Thursday, Lenovo and IBM issued a separate global recall of about 526,000 Sony-made laptop computer batteries.

The recall came days after Lenovo confirmed that one of its ThinkPad T43 laptops overheated and caught fire in Los Angeles International Airport on Sept. 16.

The batteries were sold with laptop computers and separately between February 2005 and this month, and affect five to 10 per cent of ThinkPad laptops sold in that period, Lenovo said in a statement. No information was immediately available on how many of the batteries in question have been sold in Canada.

Lenovo, the world's No. 3 maker of personal computers, said it would replace the affected lithium-ion batteries for free. Affected models include computers in the company's T Series (T43, T43p, T60), X Series (X60, X60s) and R Series (R51e, R52, R60, R60e). The recall potentially affects any computer in the T4x and R5x series since the batteries were also sold separately as an extra power source.

Apple recalled 1.8 million Sony-made batteries for its laptops in August. Owners of laptops affected by the battery recalls have had restrictions imposed on them by airlines that include Virgin Atlantic Airways, Ltd., Qantas Airways Ltd. and Korean Air.

The latest announcements bring the tally of recalled Sony batteries to about seven million worldwide.

With files from the Associated Press