The claim, seeking damages and injunctive relief, was filed in the Northern District of California and alleges that QIPC's Intelligent Density System infringes US patent 5,412,577. According to the company, the founders and owners of QIPC are former QuadTech employees.

QuadTech president Karl Fritchen said: "We have a large worldwide patent portfolio. QuadTech invests a lot of time and money in developing our industry-leading technology and we will continue to vigourously protect our intellectual property wherever and whenever our patents are infringed."

However, a spokeswoman for QIPC said: "We have not received any official documentation or any other kind of correspondence about this from QuadTech.

"Only when we will receive official documentation will we be able to give back an official statement."

The legal action in California is the third such action against QIPC by QuadTech.

In June 2008, a German court in Düsseldorf ruled in QuadTech's favour in a similar infringement case and granted an injunction to prevent QIPC selling its markless register control MRC system.

The Court of Appeals in Germany later upheld the injunction granted against QIPC.

A year later, QuadTech filed a legal action in the US District Court alleging that QIPC's MRC, sold in both mark and markless mode, infringed US patent 5,412,577. The trial date for the case in Pennsylvania has not yet been set.

QuadTech produces press control technology and sells its automated auxiliary control systems to the web offset newspaper and commercial, packaging and publication gravure markets.