A strike by air traffic controllers disrupted travel across France on Wednesday with one in five flights from Paris's main international airport Charles de Gaulle cancelled, authorities said.
Half of all flights were also cancelled from Paris's second biggest airport, Orly, which serves domestic and some international destinations, air transport authority DGAC said.
It said disruption was expected at most French airports due to the strike, which comes as many people are leaving for their summer holidays.
Unions called the strike to protest against plans to merge to French air traffic control into a European-wide system.
The action was scheduled to run until Thursday morning, they said.