An FBI agent in Buffalo, in upstate New York, said the FBI had interviewed the man and ''several'' others who were brought over the border from Canada in recent days, but none were being held by the FBI and instead were turned over to U.S. immigration officials.

U.S. authorities had no reason to suspect any of those interviewed had links to the terror attacks in New York and Washington, said special agent Paul Moskal, and the people were questioned ''as an abundance of caution.''

Neither the FBI nor Sgt. Greg Peters, spokesman for the Royal Canadian Mounted Police, would identify the man detained Sunday or any other people questioned.

The man had been held by Canadian immigration officials since Tuesday, when his U.S.-bound flight was diverted to Canada when U.S. airspace was closed following the attacks, the RCMP said Friday. Canadian immigration refused him entry, and he was offered the choice of returning to his departure point or proceeding to his intended destination. He chose to go to the United States, said Huguette Shouldice, a Canadian immigration spokeswoman.

He was escorted to the border Sunday and turned over to U.S. authorities, Peters said, declining to specify which border crossing.

On Friday, RCMP Corp. Benoit Desjardins said the man was being investigated for a possible connection to the hijackings and crashing of four planes in the United States.

Newspaper reports said the man was on a flight from Amsterdam, The Netherlands, to Detroit and was carrying Palestinian Authority travel documents and a picture of himself in a flight crew uniform against a fake backdrop of the World Trade Center.

Law enforcement officials took two men into custody in New York as possible material witnesses, the Justice Department said.