An American couple on the flight, Kurt and Lori Haskell, claimed that they saw a tall, well-dressed man aged about 50 with the suspect Umar Farouk Abdulmutallab on Friday morning at Amsterdam’s Schiphol Airport.

The Haskells have claimed the man spoke for Abdulmutallab and attempted to get him aboard Northwest flight 253 without a passport.

“At this moment we have no information on whether there was another guy,” the military police spokesman said. “We are checking all clues and information we get.”

The spokesman added that the military police and the counter-terrorism agency NCTb were reviewing CCTV video and other evidence to see if the accomplice story bears out.

The military police have already said Abdulmutallab did not go through passport control at Schiphol when he arrived from Lagos.

But the spokesman said it would be unlikely the man could board the plane without showing his passport at some point in the boarding process.