All detainees held by American forces across the world, including those imprisoned in Guantanamo Bay, Cuba, are now entitled to protection under the Geneva Conventions, the White House announced today.

The striking reversal of policy comes less than two weeks after the US Supreme Court ruled that a system of tribunals set up to try the Guantanamo Bay detainees was illegal and that the Bush Administrationn had over-reached its executive powers.

In the months after the September 11 attacks, President Bush declared that the new, border-less conditions of the War On Terror meant that those fighting the US were "illegal enemy combatants" rather than traditional soldiers in the uniform of national armies.

A memo written by the US Attorney General, Alberto Gonzales, in January 2002 set out the legal architecture of the campaign against terrorism and said that the need for rapid interrogation to prevent further attacks rendered the Geneva Conventions "quaint" and "obsolete".

Since then, the prisoner abuse scandals at Abu Ghraib prison in Iraq, hunger strikes and the ongoing legal uncertainty of the detention of suspects at Guantanamo Bay and allegations of torture during so-called "extraordinary renditions" by the CIA have prompted international calls for America to revise its treatment of detainees.

Last year, against the will of the White House, the Senate passed legislation expressly forbidding torture.

Today's announcement came just hours before the Senate Judiciary Committee began hearing evidence from military lawyers, both serving and retired, on how best to devise a new legal system for the Guantanamo Bay inmates.

The change in policy, outlined in an internal Pentagon memo, appears directed at one of the Supreme Court's clearest statements on June 30: that all detainees are entitled to the provisions known as "Common Article 3" of the Geneva Conventions.

Among other things, the article prohibits "at any time and in any place whatsoever... outrages on personal dignity, in particular humiliating and degrading treatment."

The White House Press Secretary, Tony Snow, denied that today's announcement constituted a reversal of policy but said it was part of the process of working with Congress "to find a way properly to try people who have been plucked off the battlefields who are not combatants in the traditional sense".

"The Supreme Court pretty much said it’s over to you guys to figure out how to do this," he told reporters.

"And that is where this is headed. And we look forward to working with Congress on this."

Miltary lawyers whose advice was ignored by the Bush Administration in the days after September 11 said that they hoped senators would now take the opportunity to bring America's treatment of terror suspects into line with international law, rather than attempt to design another, individually tailored set of rules.

Brigadier General David Brahms, the former chief lawyer for the Marine Corps, told The New York Times that it was vital for America to observe international law because of the risks posed to US personnel captured in the War on Terror.

"Our central theme in all this has always been our great concern about reciprocity," he said. "We don't want someone saying they've got our folks as captives and we're going to do to them exactly what you've done because we no longer hold any moral high ground."

Times Recommends

• Rio Tinto four held as China prepares case
• Diplomats must keep heads down and trousers up
• When in Rome should one make like Berlusconi?