Matsushita Electric has filed for an injunction in Japan to stop sales of PDPs (plasma display panels) by the Japanese unit of LG Electronics, and requested Tokyo's customs authorities stop imports of plasma panels from now.

Matsushita, better known for its Panasonic brand, filed the injunction and request after more than a year of talks with LG Electronics over the South Korean company's failure to recognise two of Matsushita's patents on heat dissipation technology, according to Panasonic spokesman Yoshihiro Kitadeya.

"We approached them last summer over the two patents and we had another round of discussions starting June this year, but we couldn't get a positive response as of October. Unfortunately, there is no agreement, in fact it's more like a breakdown, and we decided their time is up," Kitadeya said.

LG Electronics put out a statement calling the move by Matsushita very regrettable and unjust, but that it also held patents related to plasma display and computer technologies and the two companies had begun discussing a cross-license agreements over various patents this August.

LG Japan said it was discussing its response with its parent company and intended to take a strong stand against Matsushita. It will try to get the injunction and import ban declared invalid, it said.

Matsushita first contacted LG in August 2003 about the alleged patent infringements and LG responded with claims of its own in August 2004. Since then, the companies had been negotiating their positions on five patents, but after four rounds of negotiations, Matsushita had asked LG to pay patent fees, which was disputed by LG.

This is the second major legal spat between a Japanese and a Korean electronics company over intellectual property issues related to plasma displays as Japanese companies attempt to assert their rights against competitors in a hotly-contested and rapidly growing plasma display and TV market.

This April, Fujitsu also asked Tokyo customs to bar imports of panels from Samsung, alleging infringement of a single Japanese patent. A second lawsuit was launched in Los Angeles against Samsung alleging infringement of 10 other patents. That dispute between Fujitsu and Samsung was settled in June.

Plasma technology is proving increasing popular for displays and TVs with screen sizes of 37 inches across the diagonal and bigger. Panasonic claims to be the world's number one maker of plasma panels with a 23.1 percent market share of about 790,000 panels produced globally during April to June this year. Samsung came second with 22.5 percent and LG Electronics third with 20.5 percent.

Panasonic said that the number of panels made by LG and imported to Japan by LG Japan was not very large. "It's not a matter of damage to our business, it's more an intellectual property issue. In a sense, we are asking them to play by the global rules," Kitadeya said.