Japanese makers' share of the market for lithium-ion batteries in consumer electronics continued to fall in 2012, widening the gap with their South Korean rivals, who topped the ranking for the first time the previous year.

Three Japanese makers — Panasonic Corp., Sony Corp. and Hitachi Maxell Ltd. — together accounted for 31.2 percent of the 4.38 billion cells used in gadgets like personal computers, mobile phones and tablets shipped last year.

This was second best after the 41.2 percent held by South Korea's Samsung SDI and LG Chem Ltd., according to Techno Systems Research Co.

In 2011, the South Korean makers marked the top share for the first time with 39.5 percent, while Japan logged 34.8 percent, the Japanese research institute said Wednesday.

"Japan's share started to decline in 2008 amid the yen's surge and the won's decline against the dollar," said Renzo Yamamoto, a marketing analyst at Techno Systems.

Tomomi Saito, the analyst in charge of lithium-ion batteries at Mizuho Bank, said South Korean makers helped themselves with a strategic price reduction.

"Amid the price competition, it would be hard for Japanese makers to turn around their declining shares," she said, adding that they will have to fight to hold onto their still-strong presence in batteries for electric vehicles.

Also in 2012, Chinese battery makers made their presence felt, Techno Systems' Yamamoto said. Their share rose to 19.7 percent from 17.7 percent a year earlier.

After Sony was the first company to commercialize lithium-ion batteries in 1991, Japanese firms dominated the world market, holding about 50 percent until 2007 .

The downturn may add to the pressure for the industry players to integrate amid the stepped-up competition, experts say.

Indeed, the corporate turnaround fund Innovation Network Corp. of Japan reportedly encouraged Sony, NEC Corp. and Nissan Motor Co. in January to merge their lithium-ion battery businesses in the face of the intensifying international competition.