Sarah Ross, a spokeswoman for Senate Intelligence Committee chairman Pat Roberts, said the committee will look into the forgery, but Roberts believes it is inappropriate for the FBI to investigate at this point.

The documents indicated that Iraq tried to by uranium from Niger, the West African nation that is the third-largest producer of mined uranium, Niger's largest export. The documents had been provided to U.S. officials by a third country, which has not been identified.

A U.S. government official, who spoke on the condition of anonymity, said it was unclear who first created the documents. The official said American suspicions remain about an Iraq-Niger uranium connection because of other, still-credible evidence that the official refused to specify.

In December, the State Department used the information to support its case that Iraq was lying about its weapons programs. But on March 7, Mohammed ElBaradei, head of the International Atomic Energy Agency, told the U.N. Security Council that the documents were forgeries.

Rockefeller said U.S. worries about Iraqi nuclear weapons were not based primarily on the documents, but "there is a possibility that the fabrication of these documents may be part of a larger deception campaign aimed at manipulating public opinion and foreign policy regarding Iraq."