Ryanair has said it will cut capacity by 20% in September and October following “notably weakened” bookings in recent days.
The airline said the drop was driven by “uncertainty over recent Covid case rates in some EU countries”.
It said reductions will be in flight numbers as opposed to route closures.
Ryanair said the cuts will be “heavily focused” on areas like Spain and France where virus rates have led to the UK reintroducing travel restrictions.
The airline increased flights to 60% of its normal schedule this month after resuming services in July.
But on Monday a spokesman for Ryanair said: “These capacity cuts and frequency reductions for the months of September and October are unavoidable given the recent weakness in forward bookings due to Covid restrictions in a number of EU countries.”