Two top al Qaeda operatives held in secret U.S. custody have said that a Moroccan man on trial in Hamburg on charges of helping the Sept. 11, 2001, hijackers knew nothing of the plan for suicide attacks, according to a U.S. Justice Department statement read to the court Wednesday.

The statement summarizes information from interrogations of Ramzi Binalshibh and Khalid Sheik Mohammed, who investigators say played central roles in organizing the hijackings.

The department cautioned that the two might have been "intentionally withholding information and employing counter-interrogation techniques," but said that both indicated the Hamburg-based cell that led the attacks was much smaller than German prosecutors contend. By this account, the defendant, Mounir Motassadeq, was friends with the hijackers but unaware of their plans.

Investigators have long tried to determine how the plotters kept such complex plans secret for so long. If the prisoners' statements are true, one method was to strictly limit the number of people with specific knowledge; some theories hold that some of the hijackers did not know they were on a suicide mission.

Motassadeq, 30, was convicted last year of membership in a terrorist organization and 3,066 counts of accessory to murder. In a setback for the German government's attempts to jail people it considers remnants of the Hamburg cell, an appeals court overturned that verdict and ordered a new trial, citing U.S. refusal to provide evidence from the al Qaeda prisoners.

In the second trial, the U.S. government has shifted course and is providing some unclassified evidence.

Prosecutors contend that through repeated acts such as paying bills for absent hijackers, Motassadeq was a knowing participant in the conspiracy, which he denies. The question of advance knowledge has emerged as the trial's central issue.

Stefan Oeter, a law professor at the Hamburg University Institute of International Affairs, called the Justice Department statement a turning point in the defense's favor. "All in all, the evidence reinforces the doubt" that Motassadeq knew about the plot, he said.

Under normal circumstances, Oeter said, the court would have an easier time determining whether the prisoners were lying to protect Motassadeq. But because the court cannot question the men directly and is forced to rely on select information from U.S. officials, it has little choice but to take the testimony at face value and decide in Motassadeq's favor, he said.

The U.S. statement says the two prisoners and a third in whom the court is interested, Mohamedou Ould Slahi, a Mauritanian who formerly lived in Germany and is now in U.S. custody, will not be made available to the court. But it goes on to summarize what U.S. officials deemed to be relevant interrogation statements.

It says Binalshibh had listed men who had "no knowledge of and did not participate in any facets of the 11 September operational plan." They include Motassadeq and another Moroccan, Abdelghani Mzoudi, who was acquitted in Germany of identical charges. The statement also lists Said Bahaji and Zakariya Essabar, being sought under German arrest warrants, and Mohammed Haydar Zammar, a naturalized German and alleged al Qaeda recruiter arrested in Morocco in November 2001 and handed over to Syria, the country of his birth.

Binalshibh acknowledged visiting Motassadeq in his student housing two to three times a month, confirmed that Motassadeq received weapons training in Afghanistan and stated that Motassadeq transferred money to hijacker Marwan Al-Shehhi, who piloted one of the planes that hit the World Trade Center.

But the U.S. statement also says, "Binalshibh never told Motassadeq why Al-Shehhi needed the money, or where he was. Motassadeq, according to Binalshibh, was not aware of Al-Shehhi's whereabouts during Al-Shehhi's time in the United States," where he attended flight school.

According to the statement, Mohammed recognized a photo of Motassadeq as someone he met in Karachi, Pakistan, in late 2000 or early 2001, en route to a camp. It said they "discussed nothing operational, that they just talked about Motassadeq's Moroccan background and his Russian wife and that he was studying in Germany and was friends with Binalshibh and Mohamed Atta," often called the lead conspirator.

"Khalid Sheik Mohammed said that at no time did he personally tell Motassadeq about the 11 September attack or of the role played by Binalshibh, Atta and the Hamburg cell. Khalid Sheik Mohammed also stated that he did not believe Binalshibh would have told Motassadeq of the . . . operation because of security concerns."

In court Tuesday, defense attorney Josef Graessle-Muenscher said that any evidence from the prisoners would be tainted by U.S. abuse of prisoners. In a telephone interview after Wednesday's session, he called the U.S. statement "an extremely good, clear signal. . . . This is surprisingly much better evidence than we anticipated."

According to reports from Hamburg, federal prosecutor Walter Hemberger played down the evidence in court, saying that "people are being protected here."

Defendant Mounir Motassadeq, left, speaks with attorney Udo Jacob before court session in Hamburg.