WASHINGTON - The Defence Department said Friday it will appeal the decisions of two judges who earlier this week stalled the military's move to put detainees at Guantanamo Bay on trial.

Pentagon spokesman Bryan Whitman said the department is filing a motion with the judges to reconsider their rulings, saying that the problem is largely semantics.

Military judges ruled Monday that the Pentagon could not prosecute Salim Ahmed Hamdan and Omar Khadr, a Canadian citizen, because they had not first been identified as "unlawful'' enemy combatants, as required by a law passed last year by Congress. Khadr and Hamdan previously had been identified by military panels here only as enemy combatants, lacking the critical "unlawful'' designation.

Whitman called the issue a slight difference in terminology that should be settled quickly. He said the motion for reconsideration would be filed Friday.

"There is no material difference between the term enemy combatant used by the combatant status review tribunal process and the term unlawful enemy combatant as utilized in the military commissions act, as it pertains to the individuals in question,'' said Whitman.

He said the department reviewed various options and opted to go back to the original two judges with a renewed legal argument.

Hamdan, of Yemen, is believed to have been chauffeur to al-Qaida leader Osama bin Laden. Khadr was arrested at age 15 on an Afghan battlefield, accused of killing a U.S. soldier.

The decision dealt a blow to the Bush administration in its efforts to begin prosecuting dozens of detainees regarded as the nation's most dangerous terrorist suspects.

The two detainees are the only ones currently in the roughly 380-prisoner population at Guantanamo who have been charged with crimes under a reconstituted military trial system.

One other detainee charged under the new system, Australian David Hicks, pleaded guilty in March to providing material support to al-Qaida and is serving a nine-month sentence in Australia.

Last year, Republicans and the White House pushed through legislation authorizing the war-crimes trials after the Supreme Court threw out President George W. Bush's previous system as illegal and in violation of international treaties.

Bush established the specialized tribunal system shortly after the Sept. 11, 2001, attacks but had not been able to convict any terrorists because of legal hurdles.