Officials say suicide bombings are often carried out by foreigners. The New York Times carried a report on its Web site late Wednesday that quoted senior American military officials as saying that Saudi Arabia and Libya were the source of about 60 percent of the foreign fighters who came to Iraq in the past year to serve as suicide bombers or to facilitate other attacks.

The report said that data came largely from documents and computers discovered in September, when a U.S. raid near the Syrian border targeted insurgents believed to be responsible for smuggling the vast majority of foreign fighters into Iraq.

''I think that we're all thankful for the commitment Iran has made to reduce the flow of its weapons and explosives and training into Iraq,'' said Lt. Gen. James Dubik, the U.S. commander in charge of training and equipping Iraqi forces.