Khartoum - A Sudanese court has upheld a death sentence against four Islamists who shot dead a US envoy on 1 January 2008.

John Granville, 33, and his Sudanese driver Abdelrahman Abbas Rahama were killed as they returned from a New Year's Eve party in Khartoum.

Mr Granville's mother had earlier asked for the death sentence to be passed.

Under Sudan's Islamic law, the family of a murder victim can either request the death penalty for those convicted, forgive them or ask for compensation.

The four have always protested their innocence, saying their videotaped confessions were extracted under torture.

The incident shocked many people, including the small Western community in Khartoum.

The Sudanese capital had previously been considered one of the safest in Africa.

The Sudanese authorities condemned the attack immediately, and seem to have made resolving the case a priority, our reporter says.