The assertions clash with statements by US President George Bush's government, which has maintained- as Vice President Dick Cheney once put it - that the Guantanamo detainees are "the worst of a very bad lot" of suspected foreign "terrorists".
The Times' report on Monday cited interviews with high level US and foreign military, intelligence and law-enforcement officials.
US officials have claimed that information obtained in Guantanamo have halted al-Qaida attacks and produced vital information about the network.
But officials told the Times that Guantanamo detainees have provided only a tiny amount of intelligence of current value.
None of the Guantanamo detainees are leaders or senior members of al-Qaida and only about two dozen - possibly less-are sworn al-Qaida fighters able to give valuable insight into the network, said the Times.
There have been reports of
prisoner abuse at Camp X-Ray
"When you have the overall mosaic of all the intelligence picked up all over the world, Guantanamo provided a very small piece of that mosaic," a senior US official who has reviewed the intelligence told the Times, speaking on condition of anonymity.
"It's been helpful and valuable in certain areas. Was it the mother lode of intelligence? No," the official said.
Brigadier General Jay Hood, who heads the task force that runs the Guantanamo prison, told the Times that the expectations "may have been too high at the outset.
"There are those who expected a flow of intelligence that would help us break the most sophisticated terror organisation in a matter of months. But that hasn't happened," he told the newspaper.
According to the Times, a September 2002 top secret CIA study suggested that many of the detainees appeared to be low-level Taliban supporters or innocent civilians.
Washington has classified the Guantanamo prisoners as "illegal combatants" rather than as prisoners of war, drawing worldwide criticism from governments and human rights groups.
Charges have been laid against only a handful of the detainees from 42 countries being held at the base.