Washington  - US President Barack Obama has abandoned holding detainees at Guantanamo Bay as "enemy combatants," and will instead use the authority to do so already provided by Congress and under international law, the US Justice Department said Friday.

In a document filed in federal court, the Justice Department broke with the Bush administration, which argued the president had the sole legal discretion as commander-in-chief to order the detention of captives in the war on terrorism.

The Obama administration will now hold detainees determined to have planned or participated in terrorist attacks, or to have provided to the Taliban or al-Qaeda "substantial support," a term the Justice Department did not define but said must be determined on a case-by-case basis.

"As we work towards developing a new policy to govern detainees, it is essential that we operate in a manner that strengthens our national security, is consistent with our values, and is governed by law," Attorney General Holder said. "The change we've made today meets each of those standards and will make our nation stronger."

The continued detention of detainees at Guantanamo Bay will now be governed by international law and congressional legislation authorizing military force in Afghanistan shortly after the September 11, 2001 terrorist attacks.

The legislation, however, already recognized the president's right to hold prisoners, meaning the shift by the Justice Department announced Friday is more symbolic and will have little practical effect.

The Justice Department said as it conducts the ongoing review of detentions policies at Guantanano, it reserves the right to refine the basis for holding detainees at a later date.

Former president George W Bush declared his right to hold detainees as enemy combatants without providing them "prisoner of war" status under the Geneva Conventions. That position had been challenged in federal courts.

Days after taking office in January, Obama ordered the closure of the controversial Guantanamo prison camp within one year, and ordered a comprehensive review of the remaining 245 detainee cases. (dpa)