BLACKBERRY owners in Britain could be cut off from using their handheld computer-cum-phones if the software company loses a key court ruling expected before January 12.

BlackBerry, which is owned by the Canadian company Research In Motion (RIM), is being sued by Inpro, an intellectual property company based in Luxembourg.

Inpro claims that it owns the patent for a piece of technology that allows data to move from a computer to a handheld device. It claims that this technology is being used illegally by BlackBerry. Inpro patented the technology in April 1996.

The Times has learnt that final submissions will be made at the High Court on Monday and the trial is expected to be over by Tuesday.

If the court finds against BlackBerry it could mean that the 375,000 BlackBerry users in Britain could lose their service. But it is thought to be more likely that the judge may force RIM either to make a financial settlement or to make drastic changes to its technology, should it lose the case.

The BlackBerry has been nicknamed the “CrackBerry” because many users claim that the device, which allows them to send and receive e-mails from their phone, has become addictive.

RIM denies any patent infringement and has counter-claimed that Inpro’s patent is invalid because the technology patented by Inpro was not new or inventive. It has assembled evidence from a number of universities and technology companies to try to show the technology was created before 1996. Witnesses include representatives from University College London and the University of California, Berkeley.

If the Ontario-based company loses the case, it may be forced along with licensees such as T-Mobile International to stop selling or supporting the devices in Britain, according to lawyers.

The judge is believed to be aiming to reach his decision before the start of a similar German infringement hearing on January 12. Inpro is also trying to stop RIM and BlackBerry licensee T-Mobile International in Germany from selling or supporting the devices.

The London trial comes after another case in the United States, where BlackBerry has been accused of patent infringement by a different patent holding company, NTP.

In 2003 NTP won a $450 million settlement claiming RIM infringed its patent. Last month a US district court judge ruled that the settlement was not valid, raising fears that a court injunction would shut off access to the BlackBerry service.

Even the US federal government has entered the case. It said that it had become dependent on BlackBerrys and wants to make sure that federal workers would not be cut off from mobile access to their e-mail.

RIM, which has 3.65 million BlackBerry subscribers and is listed on the Nasdaq and Toronto exchanges, has seen its stock plunge more than 20 per cent in the past year on the back of an uncertain future.

LURE OF THE CRACKBERRY

Alastair Campbell was at the centre of attacks on Labour's campaigning style this year after accidentally sending BBC journalists an e-mail from his BlackBerry expressing his disdain for the corporation in strong terms.