All detainees held by the US military are entitled to humane treatment and are protected by the Geneva Conventions on prisoners of war, US authorities have said.
The US Defense Department outlined the new policy in an internal memo.
The document says all military detainees are entitled, under the international agreements governing the treatment of prisoners of war, to humane treatment and to certain basic legal standards when they come to trial.
President Bush's administration has been heavily criticised internationally for its treatment of prisoners at the Guantanamo Bay in Cuba.
The document is the first admission from the Pentagon that all detainees held by the US military are covered by the protections of an article of the Geneva Conventions that bars inhumane treatment.
The memo follows a June 29th Supreme Court ruling that struck down as illegal the military tribunal system set up by the Bush administration to try those held at the US naval base in Cuba.
The United States has previously determined that certain prisoners taken in Washington's "war on terrorism" are not deserving of all of the protections of the Geneva Conventions.
An inquiry by the Parliamentary Assembly of the Council of Europe (PACE) concluded last month that "authorities in several European countries actively participated with the CIA" the so-called 'rendition' or unlawful transfer of prisoners by the US authorities.
The Assembly called on the 46 member states of the Council of Europe to ensure an end to rendition and secret detention and the transfer of any individual to a place where they risk serious violations of their human rights.
It also called on the US and European states to begin full, independent I investigations into renditions and secret detentions.
Additional reporting: Reuters