Pentagon officials were plotting their next move yesterday and weighing up the possibility of an appeal after military judges dismissed war crimes charges against two Guantanamo detainees.

The decision has once again thrown into turmoil Washington’s efforts to put terror suspects on trial in military courts. In five years there has been only one conviction — that of an Australian whose plea bargain allowed him to serve a much-reduced sentence in his own country.

Since being established in 2002, the prison camp at the US naval base in Guantanamo Bay, Cuba, where about 380 detainees are held without legal rights, has inflicted huge damage on America’s reputation and become a symbol for the anti-war movement.

Britain is among the US allies which have demanded its closure, and its continued existence is known to divide even senior figures within the Bush Administration.

Commander Jeffrey Gordon, a spokesman for the Pentagon, said: “We’re reviewing the judges’ rulings and will be making a determination soon about where we go from here.”

Tony Fratto, a White House spokesman, said that the collapse of the cases against Omar Khadr and Salim Ahmed Hamdan did not mean that the military courts system was wrong. “We don’t agree with the judges’ ruling,” he said, adding that the Pentagon had asked for time to decide whether to appeal the decision.

Charges against Mr Khadr, who was 15 at the time of his capture and is accused of killing an American soldier in Afghanistan, and Mr Hamdan, who is charged with being Osama bin Laden’s driver, were dismissed because they were classified by Guantanamo tribunals as “enemy combatants”. Legislation written last year allows only “unlawful enemy combatants” to be tried in the military commissions. This law was rushed through Congress after the US Supreme Court ruled that the previous system introduced by the Bush Administration was unconstitutional.

“The fundamental problem is that the law was not carefully written,” Madeline Morris, a Duke University law professor, said. “It was rushed through in a flurry of political pressure from the White House — and it is quite riddled with internal contradictions and anomalies.”

Commander Gordon said that the entire Guantanamo system dealt with people who act as “unlawful enemy combatants”, operating outside any internationally recognised military, without the uniforms or insignia that would make them party to the Geneva Conventions. “It is our belief that the concept was implicit that all the Guantanamo detainees who were designated as ‘enemy combatants’ were in fact unlawful.”

He said that options now included seeking a reclassification of the Guantanamo Bay detainees in separate “combatant status review tribunals” or appealing the judges’ decision that their courts had no jurisdiction over whether the suspects were unlawful.

Marine Colonel Dwight Sullivan, chief of military defence attorneys at Guantanamo Bay, said that the rulings could spell the end of the war-crimes trial system. “It is not just a technicality; it’s the latest demonstration that this newest system just does not work. It is a system of justice that does not comport with American values,” he said.

The dismissals of their cases do not spell freedom for Mr Khadr or Mr Hamdan. But Mr Hamdan’s military attorney, Lieutenant-Commander Charles Swift, said that his client is relieved by the ruling. “He hopes he gets a fair trial and, like the rest of us, is patiently waiting for it.”

Arlen Specter, the Republican Senator, is among senior figures on Capitol Hill calling for the law to be re-evaluated. “The sense I have is that there’s an unease, an uncomfortable sense about the whole Guantanamo milieu,” he told The New York Times. “There’s just a sense of too many shortcuts in the whole process.”

Jerrold Nadler, a Democratic Congressman, said that he planned to hold hearings on the Military Commissions Act, which he said was “riddled with problems and created a process that operates outside the rule of law”.

Times Recommends

• Zardari still has to tackle tough questions
• Material evidence 'debunks' Turin Shroud
• BBC criticised over Uganda gay execution poll