All airlines flying to and from Greece will be affected by a four-hour strike by air traffic controllers today, easyJet warned.
The walk-out is planned between 2pm and 6pm local time, which is noon to 4pm GMT.
“We are doing everything possible to minimise the impact to our customers, but unfortunately we will have to cancel some flights,” easyJet said.
“We are working on alternative plans to attempt to move as many affected customers as possible and we will provide further updates.”
Ryanair said on its website: “We are not yet certain of the level of disruption expected. In the event we are forced to reschedule or cancel flights, we will update this notice accordingly.”
Meanwhile, bags were delayed for hours due to a power outage at Heathrow Terminal 5 yesterday morning.
British Airways said: “Although power has now been restored, the baggage system was not working at full capacity for a number of hours.
“As a result, some flights departed with lower than anticipated amounts of baggage.
“We are working as hard as we can to load any delayed bags on to later flights and are very sorry for the difficulties this loss of power has caused.”