WASHINGTON (AFP) - US Defense Secretary Donald Rumsfeld can authorize exceptions to a new Defense Department policy on military interrogations that bars torture and calls for "humane" treatment of detainees, a spokesman said.

The new directive lays out broad policy governing interrogations of detainees in Defense Department custody, but leaves the definition of "humane" to a separate, yet to be released directive that is still being debated within the administration.

A little noticed loophole in the directive, which was made public Tuesday, gives the secretary of defense or his deputy authority to override the policy.

"Intelligence interrogations will be conducted in accordance with applicable law, this directive and implementing plans, policies, orders, directives, and doctrine developed by DoD components and approved by USD (I), unless otherwise authorized, in writing, by the secretary of defense or deputy secretary of defense," the directive states. "USD (I)" refers to the undersecretary of defense for intelligence.

Bryan Whitman, a Pentagon spokesman, said there was nothing unusual about the caveat because a defense secretary always has the authority to change or modify policy he has made.

"Any deviation from the policy would have to be approved," he told reporters. "The secretary can make an exception to any policy."

The language in the directive echoes a struggle between the White House and members of Congress over a proposed amendment to the defense spending bill that would ban outright "cruel, inhuman and degrading treatment of prisoners in the detention of the US government."

Vice President Dick Cheney reportedly has pressed Senator John McCain, the amendment"s sponsor, to exempt the CIA from the ban.

The White House denied Tuesday it is seeking an "exemption for torture" for the CIA, despite President George W. Bush"s threat to veto the legislation.

The New York Times, meanwhile, reported Tuesday that a classified report last year warned that some interrogation procedures approved by the CIA after the September 11 attacks might violate some provisions of the United Nations Convention Against Torture.

The report by CIA inspector general John Helgerson listed 10 procedures approved in early 2002 for use against terror suspects, including one known as "waterboarding" in which a detainee is made to feel as if he is drowning, the Times said.

Helgerson did not conclude that those procedures constituted torture, but found they did appear to constitute cruel, inhuman or degrading treatment under the convention, the Times said.

The debate also has been fueled by a Washington Post report that the CIA has kept top al-Qaeda captives hidden away in a network of secret prisons around the world under conditions that might be considered cruel and inhuman.

The CIA has requested that the Justice Department investigate the leak of classified information contained in the Post report, a US official said.

Republican leaders in Congress on Tuesday also called for an investigation by the House and Senate intelligence committees into who leaked the information.

But other members of Congress, including some Republicans, said any investigation should probe the prisons themselves.