Lawyers for a Moroccan man convicted in Germany for helping plan the September 11 2001 terrorist attacks on Tuesday launched an appeal against the 15-year prison sentence handed down this week, saying they may take the case to the European Court of Justice.

Mournir al-Motassadeq was given the sentence on Monday evening by a Hamburg court, in what legal experts said would probably mark the end of a legal saga that has also strained co-operation between Germany and the United States on anti-terror measures.