Only man jailed for 11 September set to be freed after retrial order

The only person to have been convicted for the 11 September attacks looked almost certain to be set free yesterday after Germany's highest criminal court ordered his case to be retried because the United States had refused to allow a witness to testify in his favour.

Mounir el Motassadeq, 29, a Moroccan student, was convicted last year of being an accessory to murder on 3,066 counts for aiding and abetting the Hamburg al-Qa'ida cell that carried out the attacks in 2001. He was sentenced to 15 years imprisonment.

But the Federal Criminal Court in Karlsruhe quashed the conviction yesterday and ordered his case be reopened. Judges said the US Justice Department's failure to release mitigating evidence supplied by Ramzi bin al-Shibh, a suspect linked to al-Qa'ida held in custody in America, had prejudiced Mr Motassadeq's trial.

Klaus Tolksdorf, the presiding criminal court judge, said: "The fight against terrorism must not be permitted to turn into a wild and uncontrolled war.

"Justice cannot be upheld through recourse to methods which abandon its principles. The case is to be sent back to another panel of judges for a new trial and decision."

Mr Motassadeq's lawyer, Gerd Strate, welcomed the ruling and said there was every chance his client would be freed. "We will appeal against his continued detention. I don't think he will be in jail for much longer," he said.

Central to the court's decision was evidence, thought to exonerate Mr Motassadeq, that was supplied under interrogation by Mr bin al-Shibh, said to be the Hamburg cell's logistics officer and the group's main contact with al-Qa'ida. He was captured in Pakistan in 2002 and has since been held at a secret location in the United States.

During the trial in Hamburg court that led to his conviction, Mr Motassadeq admitted knowing the 11 September hijackers but he denied that he knew anything about their plans to carry out their attacks. He said that Mr bin al-Shibh could have confirmed his innocence.

But the US Justice Department said that Mr bin al-Shibh was "not available" to testify and refused to release transcripts of his interrogations to the court. The German government also declined to release the evidence, saying that it had been provided by the United States for intelligence purposes only.

Yesterday's ruling followed a decision by a Hamburg court last month to acquit Mr Motassadeq's friend, Abdelghani Mzoudi, of identical charges for lack of evidence. Mr Mzoudi was freed as a result of evidence supplied by a senior German intelligence official at his trial who quoted testimony from a "secret witness", widely believed to be Mr bin al-Shibh.

The "secret witness" said that the 11 September attacks were planned in Afghanistan and not in Hamburg. He also claimed that plans for the attack were a closely guarded secret which was known only to the Hamburg cell's leader, Mohamed Atta, and his fellow conspirators. He said Mr Mzoudi was not included in that group.

Yesterday's ruling was a major setback for German state prosecutors, who had wanted to see Mr Motassadeq's conviction confirmed. During his trial the court cited evidence against the former electrical engineering student including his payment of university tuition fees and rent for other members of the Hamburg cell. The judges concluded that he was motivated by "hatred of America and Israel" and said he had covered for the hijackers after they left Hamburg for America.