WASHINGTON - The 14 so-called "high-value'' detainees who were transferred from secret CIA prisons to Guantanamo Bay last year, including Canadian Omar Khadr, have all been declared enemy combatants and are subject to trial, the Pentagon announced Thursday.

Deputy Defence Secretary Gordon England has approved the "enemy combatant'' designation for all 14, after reviewing recommendations from their Combatant Status Review Tribunals, which took place over the last six months. Pentagon spokesman Bryan Whitman would not say Thursday when England made the decisions, but indicated that they were done over a period of time.

The detainees, including suspected planners of the Sept. 11 attacks, the USS Cole bombing and the 1998 bombings of U.S. embassies in Kenya and Tanzania, will now be thrust into a military trial system mired in legal challenges and hampered by lengthy delays.

England's ruling now allows the 14 to be held indefinitely at the detention centre and put on trial for war crimes.

But the trial system itself remains under challenge and it has been called into question by recent court rulings, including a decision by one military judge to throw out a case against Khadr over the wording of the "enemy combatant'' designation.

That judge, Army Col. Peter Brownback, said he had no choice but to throw out the case against terror Khadr because he had been classified as an "enemy combatant'' by a military panel years earlier _ and not as an "alien unlawful enemy combatant.''

He said the Military Commissions Act, signed by U.S. President George W. Bush last year, says only those classified as "unlawful'' enemy combatants can face war trials here.

Khadr, now 20, was captured when he was a 15 years old during a firefight with U.S. forces in Afghanistan in 2002. He was charged with homicide for allegedly throwing a grenade that killed a U.S. army medic during the battle in which he was also wounded.