Some 10 unions representing all Air France staff including cabin crews and ground staff have backed a call to strike on Friday March 30th and will meet again later this month to decide on further action.
It comes after unions already announced a strike for March 23rd.
Unions at the airline, for which the state holds a majority stake, are demanding a six percent pay rise, saying they should share in the airline's improved earnings after a wage freeze imposed since 2011.
Unions claim workers have seen a cut in their spending power due to stagnating wages. While they are demanding a 6 percent rise management is offering a basic increase of 1 percent to be paid in two installments and a range of incentives.
Unions have dismissed the offer as "small change".
After a meeting with Air France chiefs, who are desperate to avoid another strike after February's industrial action led to scores of cancellations, a union spokesperson said: "Management has at no time tried to resolve the situation ad has even tried to divide the workers with a proposition to individualize pay rises.
Air France staff held their first strike on February 22nd which led to half the airline's long-haul flights from Paris being cancelled. Many short haul flights were also grounded around the country.
"Air France regrets this situation and is making every effort to minimize the inconvenience this strike action may cause to its customers," it said in a statement at the time.