A French court sentenced a German convert to Islam to 18 years in prison Thursday for his role in the bombing of a synagogue in Tunisia that killed 21 people nearly eight years ago.

Christian Ganczarski, 42, maintained that he had nothing to do with the attack on the Tunisian resort island of Djerba. However, the French court ruled that Ganczarski gave the "green light" to the Tunisian suicide bomber who carried out the attack.

Prosecutors said the April 2002 attack was carried out on the orders of Khalid Sheikh Mohammed who is being tried in absentia while he remains in U.S. detention at Guantanamo Bay where he is being held for his role in the 2001 attacks in New York and Washington.

The brother of one of the Tunisian suicide bombers, Walid Naouar, received a 12-year sentence for having provided material help for the attack.

Judith Adam-Caumeil, a lawyer for the families of 14 of the German victims, said she was "satisfied," even though the sentences were less the prosecution had sought.

"Justice has been rendered in all its dignity and we are relieved," said Catherine Christiaens, the daughter of a French retiree who perished in the attack.

Sebastian Bono, Ganczarski's lawyer, said the sentence was not acceptable and that he would consider appealing the decision.

To the end, Ganczarski denied that he had committed any crime. "I am innocent," Ganczarski told the court Thursday before deliberations on the verdict and sentencing began.

The prosecution had presented a video showing Ganczarki with Osama bin Laden in January 2000, as well as a tape of a phone conversation in which Ganczarski is said to have given his blessing to the attack.

French prosecutors had said Mohammed ordered the attack that also killed five Tunisians and two French nationals. The death of the French prompted the investigation and trial in Paris.

Prosecutors also said phone taps by German police show that 24-year-old Nizar Naouar, the suicide bomber, sought Ganczarski's blessing for the attack before it was carried out.

Prosecutors contended Ganczarski was in contact with top al-Qaida officials, including bin Laden, during trips to Afghanistan and worked with the network as a computer expert.

In addition, French investigators said the suicide bomber also called Mohammed in Pakistan by satellite phone on the day of the attack. Prosecutors contend that Wahid Naouar knew an attack was planned and bought the phone that his brother used.

A month after the Tunisia attack, a statement carried in the London-based Arabic newspaper Al-Quds said the attack was carried out by the Islamic Army for the Liberation of the Holy Sites.

The group had also claimed responsibility for the 1998 bombings of the U.S. embassies in Kenya and Tanzania. U.S. investigators have long linked the Islamic Army to al-Qaida.

Mohammed has told interrogators he was the mastermind of the Sept. 11 attacks, saying he proposed the plan to bin Laden as early as 1996.