Nigeria has begun sending air marshals on flights and selectively using full-body scanners after the Christmas Day plot by a man accused of having a bomb in his underwear, officials said.

The air marshal programme began some two months ago, US ambassador to Nigeria Robin Renee Sanders said, while declining to discuss details, including whether they are sent on all flights destined for the United States.

Full-body scanners have been installed at two of Nigeria’s four international airports and are being used selectively, said Harold Demuren, the country’s head of civil aviation. Training is ongoing with the goal of having the scanners operating 24 hours a day, he said. Mr Demuren said the scanners had registered “a lot of successes,” but he declined to comment on whether that meant attack plots had been foiled.

“It’s not an American issue,” said Mr Demuren. “It’s global. The war on terror must be won.”

Nigerian national Umar Farouk Abdulmutallab, 23, has been accused of trying to blow up a US airliner on Christmas Day as it approached Detroit with explosives allegedly stitched into his underwear.

Passengers and crew were able to restrain Mr Abdulmutallab and put out a small fire aboard the flight, which was carrying 279 passengers and 11 crew members.