Four Japanese chip makers have shied away from filing an antidumping petition against South Korean rivals that, the domestic makers say, export dynamic random access memory chips to Japan at unfairly low prices, according to industry sources.

The four will not file a request with the Japanese government to impose antidumping tariffs on DRAMs from South Korea, as they apparently lag behind their South Korean and U.S. rivals in competitiveness in the global DRAM market, the sources said Thursday.

The four are NEC Corp., Toshiba Corp., Mitsubishi Electric Corp. and Hitachi Ltd.

In December, Toshiba announced it will terminate its DRAM chip production in June. Hitachi and NEC, which have a joint DRAM production operation, have said they too plan to withdraw from the market on a single firm basis.

The four chip makers were apparently at odds over whether to file the petition, with Takeshi Nakagawa, head of Toshiba's semiconductor unit, saying in December that Toshiba will not join the NEC-led move.

Hitachi and Mitsubishi -- both of which have a relatively small market share -- did not agree with the others on the financing of investigations over the scope of alleged damage caused by South Korean firms.

The four companies had hoped to block exports from South Korean chip manufacturers and then bring prices back up in the domestic DRAM market.

However, South Korean and U.S. makers have sharply increased their shares of the world's DRAM market, uprooting Japanese makers -- which used to hold 80 percent of the market.

It was also reported in early December that Micron Technology Inc. of the United States, the world's second-largest DRAM maker, and South Korea's Hynix Semiconductor Inc., the third-largest, are considering a business tieup.

Over the past two years, South Korean and Taiwanese DRAM makers have doubled their shares in the Japanese market, approaching the combined share held by Japanese chip makers, many of which have fallen into the red in the DRAM business.

Drops in DRAM prices are especially notable amid the global slump in the information technology sector. The size of the global DRAM market in 2001 was expected to shrink to a third of that in 2000.