RIM may be forced to halt sales of the Blackberry in the US

In August, a three-judge panel ruled that Research In Motion's Blackberry infringed patents held by US firm NTP.

The US Court of Appeals has now denied RIM's request that a full 12-judge panel reconsider the case.

The case will now return to the court which originally heard it in 2000, which could force Canadian firm RIM to stop selling the Blackberry in the US.

In 2003, Richmond District Court in Virginia had imposed a ruling banning sales of Blackberries in the US, its biggest market.

But implementation of the ban was frozen pending appeals.

The first, in December 2004, ruled that 11 of NTP's 16 patent infringement claims had been upheld. Another in August knocked down several more of NTP's claims, although it left seven of them intact.

The dispute with NTP had begun a year earlier when the US firm claimed RIM had infringed on a number of its patents, including its radio technology.