A former Iraqi nuclear scientist has provided American authorities parts and documents from Saddam Hussein's nuclear weapons program from over 12 years ago, a US intelligence official said Wednesday.

The scientist, Mahdi Shukur Obeidi, said he had kept the parts buried in his garden at his Baghdad home on the orders of Saddam's government, according to the intelligence official, who spoke on the condition of anonymity.

Once sanctions against Iraq ended, the material was to be dug up and used to reconstitute a program to enrich uranium to make a nuclear weapon, Obeidi claimed to US officials.

US authorities believe Obeidi's statements are credible, and they are regarded as evidence that Iraq had an effort to hide parts of its original programs from UN inspectors.

Still, the intelligence official acknowledged the find was not the "smoking gun" that US authorities are seeking to prove the Bush administration's claims that Iraq had an active program to develop a nuclear weapon.

Before the 1991 Gulf War, Obeidi headed Iraq's program to make centrifuges that would enrich uranium for nuclear weapons, the official said. Most or all of that program was dismantled after UN inspections in the early 1990s.

Details of Obeidi's activities during the past decade were not immediately available, although he was interviewed often by inspectors from the UN's International Atomic Energy Agency in 2002, the official said.

Obeidi turned over a two-foot-tall stack of documents that includes detailed designs for centrifuges, intelligence officials said. Obeidi told intelligence officials the parts from his garden were among the more difficult-to-produce components of a centrifuge.

Assembled, the components would not be useful in making much uranium. Hundreds of centrifuges are necessary to make enough to construct a nuclear weapon in such programs.

Obeidi and his family have left Iraq, the intelligence official said.

Since the war, US teams looking for evidence of Iraq's alleged chemical, biological and nuclear weapons programs have been chasing leads and tips from Iraqis who stand to win reward money offered for evidence. So far no weapons have been found.

Before the second Gulf War, US and allied intelligence agencies said they had evidence that Iraq was seeking to reconstitute its nuclear weapons program, although some of that evidence has since been debunked.

Other evidence, such as reports that Iraq tried to import precision-made tubes for centrifuges, was hotly debated, with some experts saying those tubes were for conventional weapons.

Earlier this year, the UN agency said there was no new evidence or indications that Iraq was working to revive the program.