Thousands of passengers face disruptions to their flights as French air traffic controllers begin industrial action today in what could be a six-day strike.
The first day of the industrial action, in a protest against budget cuts, has seen delays at major airports. British Airways, Ryanair, Easyjet and Flybe were among those affected.
UK airports say the strike could cause delays to flights traveling through French airspace, including those travelling to Spain.
The civil aviation agency said three-quarters of flights would be operational on average. "Flights to southern France, Spain, Portugal, Morocco, Tunisia and Algeria leaving from Paris" would be slightly less affected, with services reduced by 20 per cent.
The two biggest air controllers' unions, SNCTA and Unsa-ICNA, had both arranged to strike for six days from Tuesday, warning of "heavy disruption", but the SNCTA later called off its action.
The strike comes ahead of a June 30 deadline for France to present its budget plans for the sector over the next five years to Brussels.
The strikers are protesting against planned cuts between 2015 and 2019 that they say will threaten the "necessary performance and modernisation needed to ensure an efficient air navigation service in France."