US President Barack Obama has pledged that his country will not rest until all those behind an alleged Christmas Day plane bomb plot are held accountable.
Speaking in Hawaii, Mr Obama said he had ordered an immediate review of US terrorism databases.
Meanwhile, police are investigating claims that an accomplice may have helped the man accused of trying to blow up a flight from Amsterdam to Detroit.
A US couple on the flight, Kurt and Lori Haskell, told Reuters and other news agencies 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 Mr 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 Mr 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.
Mr Abdulmutallab's court hearing was cancelled today.
US lawyers had been expected to seek a search warrant to collect a DNA swab at a federal prison in Michigan.
A bail hearing for Mr Abdulmutallab is scheduled for 8 January in Detroit.
Earlier, University College London said Abdulmutallab 'never gave his tutors any cause for concern, and was a well mannered, quietly spoken, polite and able young man.'
In a statement, the University's Department of Mechanical Engineering said it was 'deeply shocked' about the recent news.
Delays as security tightened
Thousands of transatlantic air passengers are facing delays amid increased security measures following the attempted attack.
Despite the anticipated delays, British Airways said most flights were on time this afternoon, with only a few running about an hour behind schedule.
Passengers travelling with Virgin Atlantic were advised to arrive at the boarding gate early to minimise delays.
The Transportation Security Administration said that it had stepped up pre-flight screening in the United States and Europe.
With questions now being asked about security measures, air travellers in the US have been told to check in four hours ahead of scheduled departure times, while bomb-sniffing dogs are visible at airports across the country.
Once on board, many passengers have been told they will be unable to hold coats or blankets in their laps and will not be allowed to enter aircraft toilets for the last hour of their flights.
