The conclusion could strengthen the arguments of critics who have warned against the transfer or release of any more detainees as part of President Obama's plan to shut down the prison by January, the New York Times reported citing administration officials.

Past Pentagon reports on Guantanamo recidivism have been met with skepticism from civil liberties groups and criticised for their lack of detail, the paper noted.

Two administration officials told the Times that the report was being held up by Defense Department employees fearful of upsetting the White House, at a time when even Congressional Democrats have begun to show misgivings over Obama's plan to close Guantanamo.

To relocate the 240 prisoners now at Guantanamo Bay, administration officials told the paper that the plan will ultimately rely on some combination of sending some overseas for release, transferring others to the custody of foreign governments, and moving the rest to facilities in the US, either for military or civilian trials or, in some cases, perhaps, to be held without charges.

NYT quoted FBI director Robert S Mueller as saying that moving detainees to American prisons would bring with the risks including "the potential for individuals undertaking attacks in the United States."

But Michele A Flournoy, the under secretary of defense for policy, said of the detainees: "I think there will be some that need to end up in the United States."

The report, the paper said, is the subject of numerous Freedom of Information Act requests from news media organisations.

The report, a copy of which the NYT says made available to it, says the Pentagon believes that 74 prisoners released from Guantanamo have returned to terrorism or militant activity, making for a recidivism rate of nearly 14 per cent.

A Defence Department official said there was little will at the Pentagon to release the report because it had become politically radioactive under Obama.

"If we hold it, then everybody claims it's political and you're protecting the Obama administration," the official told the paper. "And if we let it go, then everybody says you're undermining Obama."

Previous assertions by the Pentagon that substantial numbers of former prisoners had returned to terrorism were sharply criticised by human rights groups who said the information was not credible and amounted to propaganda in favour of keeping the prison open, the paper noted.

The Pentagon began making the assertions in 2007 but stopped earlier this year, shortly before Obama took office.

Among the 74 former prisoners that the report says are again engaged in terrorism, 29 have been identified by name by the Pentagon, including 16 named for the first time in the report. The Pentagon has said that the remaining 45 could not be named because of national security and intelligence-gathering concerns.

In the report, the NYT says Pentagon confirmed that two former Guantanamo prisoners whose terrorist activities had been previously reported had indeed returned to the fight.

They are Said Ali al-Shihri, a leader of Al Qaeda's Yemeni branch suspected in a deadly bombing of the United States Embassy in Sana, Yemen's capital, last year, and Abdullah Ghulam Rasoul, an Afghan Taliban commander, who also goes by the name Mullah Abdullah Zakir.

Terrorism experts were quoted as saying that a 14 per cent recidivism rate was far lower than the rate for prisoners in the United States, which, they said, can run as high as 68 per cent three years after release.