The Obama administration in the United States may revamp and restart the Bush-era military trial system for suspected terrorists as it struggles to determine the fate of detainees held at Guantanamo Bay and fulfil a pledge to close the prison by January.

The move would further delay terrorism trials and, coupled with recent comments by U.S. military and legal officials, amounts to a public admission by President Barack Obama's team that delivering on that promise is easier said than done.

Almost immediately after taking office, Obama suspended the tribunal system and ordered a 120-day review of the cases against the 241 men — including Canadian Omar Khadr — being held at the navy prison in Cuba. That review was supposed to end May 20. But two U.S. officials said Saturday the administration wants a three-month extension.

The delay means that legal action on the detainees' cases would continue to be frozen. Neither of the U.S. officials were authorized to discuss the delay publicly and spoke on condition of anonymity.

One official said the Obama administration planned to use the extra time to ask Congress to tweak the existing military tribunals system that was created for the detainees. Critics of former president George W. Bush, who pushed Congress to create it, have said the system violated U.S. law because it limits the detainees' legal rights.

Now, faced with looming deadlines and few answers for where to transfer the detainees, the Obama administration may keep the tribunal system — with a few changes.

Gates doesn't rule out future commissions

Asked at a Senate hearing last week if the administration would abandon the Guantanamo system, U.S. Defence Secretary Robert Gates answered: "Not at all."

"The commissions are very much still on the table," Gates said, adding that nine Guantanamo detainees are already being tried in military tribunals.

Gates also alluded to the administration's likely request for Congress to tweak the law that created the Guantanamo legal system.

"Should there be any changes to the military commission law, if the decision is made to retain the military commissions?" he asked rhetorically.

Attorney General Eric Holder went further at a recent House hearing, saying the military commissions still could be used but "would be different from those that were previously in place."

Although as many as one-third of the detainees will be released or sent to other countries for trial, Holder said the administration is considering how to prosecute the rest of them.

"We'll be making, again, individualized determinations about where — for that group of people who should be tried, where they should be tried," Holder testified. Among the options he described were "military tribunals that have significant changes made to the manner in which they would be conducted."

The administration has never dismissed the possibility of using the tribunal system to try the suspected al-Qaeda, Taliban and other foreign fighters swept up and ultimately held at Guantanamo after 2001's Sept. 11 attacks.

But administration officials have said they hoped to try many in U.S. federal courts, relying on civilian prosecutors instead of on the military law.

Among the planned changes to the law, both officials said Saturday, would be limits on the evidence used against the detainees. Much of the evidence compiled against at least some of the detainees is classified and cannot be used in civilian courts without exposing the secret material.

Human rights groups pan idea

The potential 90-day delay was first reported in Saturday's editions of The New York Times. Human rights and civil liberties groups immediately criticized the idea.

"To revive a fatally flawed system that was specifically designed to evade due process and the rule of law would be a grave error and a huge step backward," Jameel Jaffer, a lawyer for the American Civil Liberties Union.

Since Obama ordered the prison closed, Republicans have seized on the issue of where the detainees will go — and the new Democratic administration's lack of a plan to deal with them.

"Closing Guantanamo is not a good option if no safe alternatives exist," Senate Minority Leader Mitch McConnell said in a statement Saturday.

Paul F. Rothstein, a Georgetown University legal ethics professor, said the dilemma highlights differences between campaign rhetoric and the realities of the courtroom.

"Once you become president and see the whole panoply of issues that you face, some of the things that seemed easy to promise or talk about during the campaign sometimes appear more difficult," Rothstein said Saturday.

"Elections are fought on big slogans without much nuance or detail. I think we want a president who responds to what he sees when he actually gets in there and sees the whole picture, rather than one who adheres rigidly to what he said before."