U.S. federal agents say Osama bin Laden's former driver did not fully cooperate with them after being captured in Afghanistan in 2001.
The agents were testifying Thursday at Guantanamo Bay, Cuba, where Salim Hamdan is on trial before a U.S. military commission on terrorism charges.
One FBI special agent said the Yemeni driver had special access to the al-Qaida leader but did not fully answer questions about the terrorist group.
U.S. officials say that after Hamdan's capture, he provided some cooperation by taking FBI agents on a tour of Bin Laden's compounds in Afghanistan's Kandahar province.
The agent said Hamdan confessed during questioning to attending an al-Qaida training camp, but expressed no interest in becoming a fighter. Defense lawyers say Hamdan was a low-level al-Qaida employee with no involvement in terrorism.
Hamdan is the first Guantanamo detainee to go on trial before the U.S. military commission. He faces life in prison if convicted.
On Wednesday, a former FBI agent testified that Hamdan heard Bin Laden rejoice in the news of the September 11, 2001 terrorist attacks on the United States.
U.S. military prosecutors say two surface-to-air missiles were found in Hamdan's vehicle when he was captured.
The U.S. detention center in Guantanamo and the military commission have come under strong domestic and international criticism. About 270 detainees remain there. Some of them have been held for years without charge.
The Bush administration has declared the detainees unlawful enemy combatants, not entitled to the rights afforded prisoners of war.
Some information for this report was provided by AFP, AP and Reuters.