The computer unit of Germany's Siemens AG has confirmed it has contacted makers of computer monitors as part of an effort to enforce a patent it holds in Europe. Siemens-Nixdorf Informations systeme AG (SNI) holds a six-year old patent for technology that puts computer monitors into a low-power mode when not in use.

The company recently distributed letters informing European competitors that their monitors may violate a patent awarded to SNI in 1992 by the European Office for Patents.

In the letter, SNI said told competitors it was "prepared to discuss with you the conditions for a non-exclusive and non-transferable licensing agreement". The letter gave the companies until September 15th to reply.

SNI spokeswoman, Ms Doris Schneider said she did not know if SNI would try to enforce the patent in the United States, where many European patents are valid.

Companies in the computer industry often allow competitors to use patented technology in exchange for a royalty payments on each product sold.