WASHINGTON, Sept. 7 — In defending the Central Intelligence Agency&a's secret network of prisons on Wednesday, President Bush said the detention system had used lawful interrogation techniques, was fully described to select members of Congress and led directly to the capture of a string of terrorists over the past four years.

A review of public documents and interviews with American officials raises questions about Mr. Bush's claims on all three fronts.

Mr. Bush described the interrogation techniques used on the C.I.A. prisoners as having been "safe, lawful and effective," and he asserted that torture had not been used. But the Bush administration has yet to make public the legal papers prepared by government lawyers that served as the basis for its determination that those procedures did not violate American or international law.

The president said the Department of Justice approved a set of aggressive interrogation practices for C.I.A. detainees in 2002 after milder ones proved ineffective on Abu Zubaydah, the first of the Qaeda leaders taken into custody.

Current and former government officials said that specific interrogation methods were addressed in a series of documents, including an August 2002 memorandum by the Justice Department that authorized the C.I.A.'s use of 20 interrogation practices.

The August 2002 document, which was leaked to reporters in 2004, said interrogation methods just short of those that might cause pain comparable to "organ failure, impairment of bodily function or even death" could be allowable without being considered torture.

The memorandum was repudiated in another Justice Department document at the end of 2004, and Congressional officials said on Thursday that they had not received documents from the administration explaining the legal underpinnings of the program.

One prisoner is known to have died in Afghanistan after interrogation by a C.I.A. contract employee, but the agency has distanced itself from that episode, and the former employee was convicted on assault charges last month in federal court in North Carolina.

Some lawmakers questioned Mr. Bush's claims that his administration fully briefed some members of Congress on details of the secret detention program.

Senator John D. Rockefeller IV of West Virginia, the ranking Democrat on the Senate Intelligence Committee, said on Wednesday that the Bush administration had "withheld details of the C.I.A. detention and interrogation program from the Congressional intelligence committees."

Congressional officials said on Thursday that the Senate Intelligence Committee was briefed about the existence of the C.I.A. detention program but was not informed about the locations of the secret prisons.

Public documents show that some of the information that led to the arrests of senior terrorism plotters like Khalid Shaikh Mohammed and Ramzi bin al-Shibh was known before the C.I.A. detained its first prisoner, Mr. Zubaydah, in the spring of 2002.

Mr. Bush said it was Mr. Zubaydah who disclosed to C.I.A. interrogators that Mr. Mohammed was the mastermind of the Sept. 11 attacks and often used the alias Mukhtar, sometimes spelled Muktar.

"This was a vital piece of intelligence that helped our intelligence community pursue K.S.M.," Mr. Bush said, referring to the terror suspect by his initials.

The report of the Sept. 11 commission said that the C.I.A. knew of the moniker for Mr. Mohammed months before the capture of Mr. Zubaydah.

According to the report, the C.I.A. unit given the task of tracking Osama bin Laden had intercepted a cable on Aug. 28, 2001, that revealed the alias of Mr. Mohammed.

Mr. Bush also said it was the interrogation of Mr. Zubaydah that identified Mr. bin al-Shibh as an accomplice in the Sept. 11 attacks.

American officials had identified Mr. bin al-Shibh's role in the attacks months before Mr. Zubaydah's capture. A December 2001 federal grand jury indictment of Zacarias Moussaoui, the so-called 20th hijacker, said that Mr. Moussaoui had received money from Mr. bin al-Shibh and that Mr. bin al-Shibh had shared an apartment with Mohamed Atta, the ringleader of the plot.

A C.I.A. spokesman said Thursday that the agency had vetted the president's speech and stood by its accuracy.

"Abu Zubaydah was the authoritative source who identified Khalid Shaikh Mohammed as the mastermind of 9/11 and the man behind the nickname Muktar," the spokesman, Paul Gimigliano, said in a statement. "His position in Al Qaeda — his access to terrorist secrets — gave his reporting exceptional weight and it gave C.I.A. insights that were truly unique and vital. Abu Zubaydah not only identified Ramzi Bin al-Shibh as a 9/11 accomplice — something that had been done before — he provided information that helped lead to his capture."

Besides the 14 prisoners identified on Wednesday, some officials and human rights advocates questioned the fate of dozens of others believed to have moved through the C.I.A. prison network over the past four years.

Human Rights Watch, in response to a request from The New York Times, provided a list of 14 men who the organization believes have been secretly detained since the Sept. 11 attacks and whose whereabouts are still unknown.

One of the men, Ibn al-Shaykh al-Libi, is believed to have given false information about links between Iraq and Al Qaeda after C.I.A. officials transferred him to Egyptian custody in 2002. Mr. al-Libi's statements were used by the Bush administration as the foundation for its claims that Iraq trained Qaeda members to use biological and chemical weapons.

It emerged later that Mr. al-Libi had fabricated these stories while in captivity to avoid harsh treatment by his Egyptian captors.

Human Rights Watch has also identified 20 other men it said were at the military prison at Guantánamo Bay, Cuba, and who the group believes were once in C.I.A. custody.

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