A German court on Friday convicted a Moroccan man and sentenced him to seven years in prison as a member of the Hamburg cell that planned the Sept. 11, 2001, attacks on the World Trade Center and the Pentagon.

But the court found Mounir Motassadeq, 31, not guilty of more than 3,000 counts of accessory to murder in the attack, ruling that he did not play a direct role in the plot.

The judge overseeing the Motassadeq retrial, Ernst-Rainer Schudt, criticized the U.S. government for refusing to allow the court to interview or have access to several captured al Qaeda leaders who could have shed light on the inner workings of the Hamburg cell. He also accused U.S. authorities of stonewalling requests for information and of being uncooperative during the trial.

"The point is, we would have liked to have questioned them ourselves," Schudt said of the imprisoned al Qaeda leaders.

The U.S. Justice Department provided the German court with written summaries of interrogations of some al Qaeda leaders, including chief plotters Ramzi Binalshibh and Khalid Sheik Mohammed. But U.S. officials said it would pose a risk to national security to allow the captives, who are being held at undisclosed locations, to be cross-examined or questioned in greater detail.

German government officials, who have faced criticism for their inability to win convictions in other terrorism cases, praised the verdict. "A clear signal has been sent of the determination of the state in the fight against terrorism," Interior Minister Otto Schily said in a statement.

At his first trial in 2003, Motassadeq was convicted of all the charges and sentenced to 15 years in prison, the maximum punishment in Germany. But an appellate court overturned the verdict, and prosecutors feared they would have trouble winning the case the second time around.

Motassadeq, who moved to Hamburg in the mid 1990s and became close friends with lead hijacker Mohamed Atta and other ringleaders of the attacks, spent about 2 1/2 years in prison between his November 2001 arrest and his release in April 2004. He was taken into custody again on Friday to begin serving his sentence. Prosecutors and defense lawyers said they would appeal the decision, which came at the end of a year-long retrial.

The Motassadeq case underlines the difficulties the United States and its allies have faced in trying to win convictions against those suspected of helping carry out the Sept. 11 attacks. Zacarias Moussaoui, a French citizen of Moroccan descent, pleaded guilty in U.S. federal court in April to conspiracy charges related to the hijacking plot, although his exact role remains unclear. Three accused members of al Qaeda are on trial in Spain on charges that they assisted the hijackers. A verdict in that case is expected next month.

According to testimony during the retrial, Motassadeq helped conceal the whereabouts of two of the Sept. 11 hijackers after they left for the United States, paying their rent and performing other tasks on their behalf. He also traveled to Afghanistan with other members of the Hamburg cell to receive military training and meet al Qaeda leaders, witnesses said.

Prosecutors, however, were unable to prove that Motassadeq had concrete knowledge of the hijacking plot. "The clear picture shows the defendant as a member of a terrorist organization, but not as an accessory to murder," Schudt said.

Dominic Puopolo Jr., a Miami Beach computer consultant whose mother was a passenger on one of the airplanes that the hijackers crashed into the World Trade Center, said he was pleased with the Hamburg court's ruling. "I'm amazed," he said, admitting that he feared Motassadeq might walk free. "I'm just filled with joy."

But Puopolo, who moved to Hamburg for several months to attend most of the trial, said his mood was bittersweet. A few hours after he learned of Motassadeq's conviction, he said he received word that he had been denied financial assistance from a Massachusetts charity set up to help family members of Sept. 11 victims.

In a telephone interview, Puopolo said the Massachusetts 9/11 Fund Inc., a non-profit group, denied his application for $9,181 in benefits. He said he had received about $200,000 from the national 9/11 Victim Compensation Fund, but used most of that to quit his job and move to Hamburg to monitor the trial.

"Here is a day where I believe I did my best to help put a man in jail," said Puopolo, a part-time Massachusetts resident. "But now I feel beaten, actually."

David Hastings, executive director of the Massachusetts 9/11 Fund, said confidentiality restrictions prevented him from commenting on individual cases.

Mounir Motassadeq was acquitted of helping to plan the 9/11 attacks.