An Italian journalist said in an interview published this morning she gave documents on Iraq seeking uranium from Niger to the US embassy in Rome in 2002 to try to find out if the information was credible.
The documents have become central to a charged debate over whether President Bush and British Prime Minister Tony Blair, knowingly or not, made exaggerated claims over Iraq's nuclear weapons program to justify going to war.
A senior State Department official said Thursday the United States had acquired the documents from "a private source, non-governmental," in Rome.
Ms Elisabetta Burba, a journalist with Italian current affairs weekly Panorama, said it was she who handed over the papers to the US embassy in October 2002 after acquiring them from a source she could not name but who was not linked to Italian secret services.
"I knew the documents could represent a huge world scoop...but there were many details that I found unconvincing," Ms Burba said in an interview with daily Corriere della Sera.
She said after checks in Niger failed to satisfy her that the documents were reliable, Panorama decided not to publish the story.
Ms Burba, meanwhile, had given the documents to US embassy officials in Rome to try to find out if they were credible.
Media reports had suggested Italy's military intelligence agency, Sismi, had passed on the false documents to US or British secret services - a suggestion which was denied by an Italian government official.
President Bush said in his annual State of the Union speech in January that the British government had information that Iraq was seeking uranium in Africa.
White House officials have said the claim should not have appeared in the speech because it did not meet the standard of reliability necessary for inclusion in a major address by the president.
But the British government has said it had other intelligence beyond the discredited documents and was sticking by the allegations.