(Recasts after sentence) By Sabine Siebold HAMBURG, Germany, Jan 8 (Reuters) - A German court sentenced a Moroccan friend of the Sept. 11 hijackers to 15 years in prison on Monday for being an accessory to mass murder. Mounir El Motassadeq, a member of a group of radical Arab students in Hamburg who helped organise the 2001 attacks, is one of only two men convicted of involvement in the plot which resulted in the death of nearly 3,000 people in the U.S.. It was the maximum sentence and in line with the demands of the Federal Prosecutor's Office. Motassadeq listened to the verdict, read out by a member of the panel of judges at the Hamburg court, without any visible signs of emotion. In November, Germany's top appeals court in Karlsruhe found the 32-year-old guilty of abetting the murder of 246 passengers and crew who died on four planes that crashed on Sept. 11, 2001. The decision overturned a 2005 ruling which convicted Motassadeq of belonging to a terrorist organisation and handed him a 7-year jail sentence, but cleared him of abetting mass murder. That court said he was a low-tier member of the group led by suicide hijacker Mohammed Atta and Motassadeq's lawyers insist he knew nothing about the plot to fly planes into targets in New York and Washington. But prosecutors successfully argued in November that under a "division of labour" within Atta's group, Motassadeq played a key role in running the financial affairs of other cell members and covering up their absence from Germany before the attacks. The Hamburg court heard arguments on Monday from both sides and rejected a petition from Motassadeq's lawyers to suspend the hearing. His lawyers had argued it was unconstitutional because it had been set up purely to determine Motassadeq's sentence. The complex and drawn-out case has strained Berlin's relations with Washington as German courts tested how far the United States would go in giving sensitive evidence. Zacarias Moussaoui, a French citizen of Moroccan descent who received a life sentence from a U.S. court in May 2006, is the only other person convicted of links to the attacks.
