The report came as the White House and the Central Intelligence Agency (CIA) have been under increasing fire for including the statement about the alleged Iraq attempt to buy uranium from Africa into President George W. Bush's State of the Union speech in January. The documents on which the claim was based turned out to be forged.

The previously undisclosed probe is being conducted by the FBI's counter-intelligence division, the Newsweek report said.

The bureau has sent agents to Italy and other countries to look into the murky origins of the documents and ordered the questioning of officials at the State Department and the CIA, said the report.

The FBI is trying to determine who forged the documents and why, and whether anyone tried to influence US foreign policy, the weekly magazine quoted officials as saying.

The disputed documents were first provided to Italian intelligence services in late 2001, and information about them was then passed along to allied intelligence agencies, including Britain's MI6 and the CIA of the United States, the report said.

But the documents didn't come into the possession of the US government until nearly a year later, in October 2002, when a foreign journalist turned them over to the US embassy in Rome, which then quickly passed them along to the CIA station chief in Rome and officials at the State Department.

But the CIA headquarters in the United States did not get the documents until early February 2003, which was after Bush's State of the Union address, the report said.

Throughout the fall and in the weeks prior to the State of the Union address, the CIA had tried to warn the White House that the intelligence reporting about Iraqi attempts to buy uranium from Niger was "fragmentary" and not reliable.

At one point, CIA director George Tenet himself personally advised deputy national-security advisor Steve Hadley to remove a reference to the uranium purchases from a speech Bush was preparing to give in Cincinnati on Oct. 7, 2002, said Newsweek.

But the idea that the documents themselves were based on forged material did not become known until after Feb. 4, 2003, when the United Nations International Atomic Energy Agency (IAEA) asked the US government to back up some of the allegations it was making about Iraq's nuclear program.

IAEA forensic analysts figured out they were forgeries, Newsweek said.

In another development, Tenet on Wednesday testified before a closed-door session with the Senate Intelligence Committee over the dubious arms data, days after he took responsibility for approving the inclusion in Bush's State of the Union speech the statement that Iraq had sought uranium in Africa.

(Xinhua News Agency July 17, 2003)