South Korean electronics major LG Electronics today said that it had filed a patent lawsuit against Japan's Hitachi in a prolonged tit-for-tat legal battle over plasma display panel (PDP) technology.

In a statement, LG Electronics said, the lawsuit was filed with the US District Court of Texas against Hitachi, its US affiliate and its PDP unit.

LG's suit is a counter suit following similar action by Hitachi. The counter suit accuses the Japanese firms of infringing LG Electronics' seven PDP-related patents and seeks a court injunction against them and monetary compensation.

"Intellectual property is one of LG's essential assets, which we will always uncompromisingly protect," said Jeong Hwan-Lee, executive vice president and head of its intellectual property centre.

"Japanese firms are filing more and more lawsuits as competition in the global display market has increased dramatically. We will proactively deal with the situation based on our patented and patent-applied-for technologies," he added.

LG and Hitachi have had inconclusive talks aimed at settling the patent dispute since 2005. Hitachi filed suit against LG Electronics at the US court for patent infringement on similar technologies in April, claiming they were Hitachi's proprietary technology.

LG Electronics said it holds some 2,300 international PDP-related patents and has applied for another 6,000. It is the world's largest producer of CDMA handsets, air conditioners, optical storage products and DVD players.