Update: The aviation authority asked Orly airport to reduce flights by a further 50 percent on Sunday from 4.00pm to 11.30pm Sunday, due to the strong support for the strike.
Six French airports were suffering delays on Sunday morning. They were:
Marseille, 40 minutes;
Toulouse, Bordeaux, Paris Orly, 30 minutes;
Paris Charles De Gaulle, Lyon, 20 minutes.
The air transport authority asked airlines to reduce their flights by 20 per cent on Sunday and Monday, based the number of air traffic controllers declaring their intention to go on strike, as required by French law.
Officials said that the situation was improving as the morning wore on.
The strike has been called by one union, the UNSA, which is the third most popular in elections to workplace committees, but the industrial action is reported to have widespread support in the profession.
The union claims that staffing levels are being cut due to the reduction of replacement of workers leaving from 80 percent to 65 percent, while traffic forecasts "indicate a perspective of substantial increase".
It also says that a lack of investment in technology has resulted in "more and more frequent breakdowns with implications for safety" and calls on the government to provide the necessary funding.