Nokia Oyj, the world’s biggest maker of mobile phones by volume, lost a UK court bid to invalidate a European patent that Germany’s IPCom GmbH & Co claims is vital to the Finnish company’s handset sales.

The patent, which covers technology for connecting a handset to a network, is valid and infringed by two Nokia devices, which Judge Christopher Floyd didn’t identify in his ruling at the High Court in London. Nokia’s shares fell as much as 3.3 per cent to a 13-year low in Helsinki trading.

“As far as we know, this is the first time that an essential telecoms 3G patent was ever upheld and judged infringed in the UK, a jurisdiction well-known for being very demanding for patent holders,” Bernhard Frohwitter, IPCom’s managing director, said in a statement.

The ruling comes two days after Nokia won an almost two- year patent dispute with Apple Inc, in a settlement that awards a one-time payment to and royalties to the Espoo, Finland-based handset maker. Nokia’s dispute with IPCom is being played out in courts in the US, Germany, Japan and Italy.

IPCom, which says the ruling threatens Nokia’s UK sales, seeks royalties from a family of mobile-technology patents it acquired in 2007 from Robert Bosch GmbH, the world’s largest automotive supplier. IPCom bought the patents after Bosch failed to license them to Nokia in 2003.

The patent at issue in today’s case wasn’t infringed by a third Nokia device, Floyd. Nokia’s shares fell 2.3 per cent to ¤4.09 at 1:29 p.m, extending their slide so far this year to 47 per cent. IPCom rejected Nokia’s interpretation of the ruling, claiming the two infringing devices are still in use by the Finnish company.