Air France is to cancel 20-30% of its flights on Saturday, day two of the European football championships, because of a pilots' strike.
Chief executive Frederic Gagey said that the company offered a new proposal in a long-running dispute over working conditions but unions rejected it.
Pilots' unions have called a strike from Saturday to Tuesday, coinciding with the starting matches of the month-long Euro 2016 tournament featuring games in cities around France.
Mr Gagey said the airline would work to limit the impact on travelling football fans but said Air France can only guarantee 70-80% of flights worldwide on Saturday.
Strikes in other sectors by unions angry at a labour reform bill may make for a difficult start to the event.