EasyJet's director general Johan Lundgren said on Wednesday he believed the disruption caused by air traffic control strikes and bad weather combined cost the company €25 million in the third quarter to June 30th.
That figure was due to the fact 2,606 flights were cancelled in the same period.
Lundgren said the repeated strikes by controllers in France “significantly impacting its operational performance and was pushing up costs.”
The easyJet chief denounced the strikers for violating one of the “four freedoms” of the EU – that of the freedom of movement of its people.
He said: “Disruption this year so far has been equivalent to all of 2017, which has been challenging, and we estimate this will not go away.”
The statement by EasyJet follows similar moves by Ryanair and British Airways owner IAG who want the EU to force France to do more to tackle repeated strikes by air traffic controllers which have led to more than 750,000 passengers having flights cancelled since the start of this year.
Ryanair chief executive Michael O'Leary said 2018 was on course to be the worst year ever for controller strikes, with 28 days lost already.
The vast majority of passengers hit by delays and cancellations due to the French strikes are not flying to or from France but travelling on routes which pass through the country's air space.
IAG chief executive Willie Walsh said he believed the French government was failing to uphold passengers' right to free movement, which is enshrined in EU law, by not tackling the repeated strikes.
A recent French senate report said the country's air traffic control was responsible for a third of all aviation delays in Europe, according to Le Parisien newspaper.
Between 2004 and 2016, French air traffic controllers were on strike for 254 days, vastly outstripping their closest rival Greece, where there were 46 days of stoppages and Italy with 37, according to the report seen by the daily.
But the European Commission, the bloc's powerful executive arm, defended workers' “fundamental right” to go on strike and said they hoped “non-binding and non-legislative” guidelines would solve the problem.
“The commission is not questioning the right to strike, which is a fundamental right of workers,” spokesman Enrico Brivio told reporters.
“The commission has proposed non-binding and non-legislative best practices,” Brivio said.
The measures include early notification of strike action and protection of overflights.