Hundreds of flights have been cancelled ahead of a planned strike by French air traffic controllers.
The SNCTA union – France’s largest – has called the strike for Wednesday and Thursday in a dispute over working conditions.
The DGAC civil aviation authority has asked airlines to cut their schedules for flights to and from France on Wednesday by 40%.
Short-haul flights are expected to be worst affected.
“Disruption is expected over the whole country,” the DGAC said in a statement.
Travellers have been advised to contact their airline.
Low-cost airline Ryanair says it has had to cancel more than 250 flights, with further cancellations likely.
“We sincerely apologise to all customers affected by this unwarranted strike action and we call on the EU and French authorities to take measures to prevent any further disruption,” said Ryanair in a statement.
“It’s grossly unfair that thousands of European travellers will once again have their travel plans disrupted by the selfish actions of a tiny number of French ATC [air traffic control] workers.”
Air France says that it expects to operate almost all its long-haul flights and 60% of its medium-haul flights to and from Paris Charles de Gaulle airport.
Travellers booked on short and medium-haul Air France flights on Wednesday or Thursday can choose to travel between 10 and 15 April instead, it said.
A particular grievance for the SNCTA is the raising of the retirement age for air traffic controllers by two years to 59.
Further action is planned between 16-18 April and 29 April-2 May.