Ryanair claimed there is a contradiction between French and EU law (Reuters)

Airline Ryanair has cancelled over 250 flights to France with more to follow, according to the company.

The SNCTA union of air traffic controllers told the French Civil Aviation Authority (DGCA) that the strike would take place on Wednesday and Thursday.

"Disruption is expected over the whole country," the DGCA said.

The Authority has asked airlines to cut their schedules for flights to and from France on Wednesday by 40%.

The SNCTA says it is unhappy about offers made on new working conditions and retirement plans, according to BBC News.

The union has also called on its members to go on strike between 16-18 April and 29 April-2 May.

"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."

The airline is offering to transfer customers' tickets to other flights or provide refunds.

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.

"Expect cancellations and major delays," warned the European Organisation for the Safety of Air Navigation on Twitter.

There are also easyJet cancellations including some return flights to Paris from Gatwick, Belfast and Luton.

A spokesperson said: "Like all airlines flying to and from France, we expect significant impact to our flights during this period.

"We can assure our passengers we are doing everything possible to limit the inconvenience of this strike on them."

British Airways was also affected by the strikes. A statement read: "We will be using larger aircraft, where possible, to help affected customers and are doing all we can to reduce any disruption.

"We will continuously review the situation on Wednesday 8 April and will look to publish our revised schedule for Thursday 9 April, during Wednesday afternoon."