nantes
It was widely reported on Friday that the man held at the airport was Xavier Dupont de Ligonnès, who is suspected of murdering his family in 2011.
The 28-year-old footballer died when a private plane crashed into the English Channel earlier this year.
The Bluebirds received a letter from the French club on Tuesday.
Football star Emiliano Sara is still missing after the aircraft he was travelling in disappeared close to the island of Guernsey on 21 January. He was on his way from Nantes to Cardiff to join his new club Cardiff City.
Youth unemployment in France is at 25 percent.