RABAT, Morroco - Morroco is opting to prosecute the alleged mastermind of Britain's biggest-ever cash robbery, rather than send him back for trial, a judicial source said Wednesday.

Ibrahim Lee Murray, 32, whose mother is English, holds British citizenship, but the supreme court in Rabat rejected Britain's request for his extradition on the grounds that - like his father - he is Moroccan as well.

"On Monday, Ibrahim Lee Murray appeared before a prosecutor who informed him that he would henceforth be prosecuted in Morocco for the Kent robbery at the request of the British authorities," the judicial source told AFP.

No trial date was given.

Moroccan law prohibits the extradition of Moroccan nationals, but it does allow for them to be tried in Morocco for alleged crimes elsewhere if another country so asks.

Murray, identified by prosecutors in London as a part-time cage fighter, is alleged to have taken part in the early-morning raid on a Securitas cash depot in Tonbridge, Kent, southeast England on February 22, 2006.

After kidnapping the depot's manager and his family, and tying up members of staff, the robbers fled with more than 53 million pounds in bank notes - the biggest-ever cash robbery in British history.

Murray was arrested in the Rabat area in June 2006 along with British national Paul Allen, who was extradited in January last year and charged with robbery, kidnapping and possession of firearms.

Allen was remanded in custody, facing retrial, after jurors in London failed to reach a verdict in his case in January this year. It was at Allen's trial that prosecutors fingered Murray as the "leading light" behind the heist.