Aer Lingus is advising passengers traveling to all UK airports not to carry hand luggage.
This comes despite the UK's Department of Transport decision today to revoke an outright ban on carry-on luggage imposed last Thursday after 23 people were arrested on suspicion that a major terrorist attack on planes traveling from London to the US was being planned.
Aer Lingus said it was awaiting awaiting advice from the British airports operator BAA before issuing more specific guidelines.
BAA said today it would be ready to accept carry-on bags but underscored new rules would limit such luggage to a single bag the size of an attache case.
Travellers can again carry mobile phones, laptops and other electronics on board but a ban remained on all liquids in carry-on luggage, except prescription medicines and baby food.
All hand-luggage would be X-rayed and all passengers boarding flights for the US faced searches at departure gates, BAA said.
Earlier Ryanair called on the British government to revise its "heavy-handed" airport security measures following the cancellation of 20 per cent of its flights from Stansted airport this weekend.
Ryanair chief executive Michael O'Leary
In a statement, the airline said the security measures "do not enhance security but are disrupting the journeys of thousands of British passengers . . . and bringing the main London airports to the point of collapse."
Ryanair said that it supports sensible security but that the British Airport Authority (BAA) cannot carry out body searches on all passengers who have just passed through security X-ray machines.
It said that the extra security should be aimed at US flights only.
"The UK Government, by insisting on these heavy handed security measures, is allowing the extremists to achieve many of their objectives," said Ryanair chief executive Michael O'Leary.
"The Government must act today otherwise these extremists will have succeeded by disrupting the economic life of Britain, its air transport industry and its citizens. We must not allow these terrorists to succeed."