A Nigerian man suspected of trying to blow up a passenger jet arriving into the US has been formally charged.

Authorities say Umar Farouk Abdulmutallab was overpowered after he attempted to set off an explosive device on a Delta Northwest airlines flight arriving into Detroit from Amsterdam on Christmas Day.

The 23-year-old remains in hospital where he is being treated for extensive burns. He has reportedly admitted having links to al Qaeda and police in London have been searching several
properties in the city where Abdulmutallab studied engineering at University College.

Investigators are still trying to figure out how the accused was able to breach security at Schiphol airport in Amsterdam.

In the meantime, surveillance at European airports has been tightened, particularly on transatlantic flights. US hubs also remain on high alert. Security has been boosted on flights with warnings that air passengers may experience more scrutiny.

In a sign of just how cautious authorities are being, a Lufthansa flight en route from Frankfurt to Detroit was forced to make an unscheduled landing in Iceland earlier on Saturday. It was found to be carrying luggage whose owner had not boarded. A bomb squad searched the Airbus but it was a false alarm.

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