US forces found documents and computers with information on the foreign fighters in a September raid on a tent camp near the town of Sinjar, close to the Syrian border, the Times said, citing senior US military officials.
The target of the raid was an insurgent cell believed to be responsible for smuggling the vast majority of foreign fighters into Iraq, the daily reported.
The documents included biographical sketches listing the hometowns of more than 700 fighters who were brought into Iraq since August 2006.
Saudi Arabia is a longtime US ally in the region, while the United States restored diplomatic relations with Libya and removed it from its list of state sponsors of terrorism last year.
But Saudis and Libyans represented the majority of foreign fighters in the Sinjar documents, the Times said.
The largest number of foreign fighters — 305, or 41 percent — came from Saudi Arabia, despite government efforts to rein in would-be terrorists after 15 of the 19 hijackers in the September 11, 2001, attacks on the United States turned out to be Saudis.
Libyans represented 137, or 18 percent, of the total foreign fighters, the senior US military officials, who were not named, told the Times.
Two of the foreign fighters came from France, but all of the others originated from predominantly Sunni Muslim countries, the newspaper said.
The third-largest source of foreign fighters was Yemen, with 68, followed by 64 from Algeria, 50 from Morocco, 38 from Tunisia, 14 from Jordan, six from Turkey and two from Egypt, it said.
