The New York Times said the information was found in documents uncovered in a U.S. military raid on an insurgents' camp near Sinjar, in northwest Iraq near the Syrian border, in September.
Material seized at the camp, believed to be used by a cell responsible for smuggling the majority of foreign fighters into Iraq, showed the home towns of more than 700 foreign militants who entered Iraq since August 2006, the newspaper said.
A total of 305 of the foreign fighters listed in the documents, or 41 percent, were from Saudi Arabia. Another 137, or 18 percent, were Libyan. Yemenis were the third largest group, the newspaper said.
Officials also concluded that the number of foreign militants entering Iraq had dropped sharply in 2007, the report said, falling from 80 to 110 per month in the first half of the year to around 40 in October.
Syrians -- via whose country many fighters are suspected of reaching Iraq -- made up 8 percent of the individuals listed.
Accusations that Syria hasn't done enough to stem that flow have long been a point of tension with Washington.
In the article, military officials said most of the fighters had flown into Damascus or entered Syria through Jordan. Some were reportedly captured and then released by Syrian authorities.
General David Petraeus, commander of U.S. forces in Iraq, has praised Syria for steps it has taken to crack down on militants entering Iraq.
"There does appear to have been more robust action by Syria against some foreign fighter networks," he told The Wall Street Journal.
He said the number of foreign fighters entering Iraq each month had dropped by at least one third.
In the interview, published on Wednesday, Petraeus struck a cautious note about the possibility of future troop reductions. as he assessed the sharp drop in violence since an extra 30,000 U.S. troops were deployed in Iraq this year.
President George W. Bush plans to bring about 20,000 troops home by July.
© Reuters 2007.