The US Transport Security Administration (TSA) has announced extra security measures at British airports which will see up to 50% of passengers facing secondary screening.
Specific details of the new methods have not yet been released, but all passengers on flights bound for America could be subject to additional searches, body scans and behavioural observation before being allowed on board.
The move is another result of the thwarted attempt to bring down a Delta Airlines flight by a Nigerian man using an explosive device hidden in his underwear on Christmas Day 2009.
Full body searches and additional hand baggage searches were among measures introduced at boarding gates for passengers originating from 14 countries such as Pakistan, Afghanistan and Iraq.
But this has now been extended so that passengers may face secondary screening, irrespective of nationality, age and gender.
The TSA has recommended that passengers “allow additional time to get through security on America-bound international flights” and urged passengers to check with their airports and carriers.