Jean-Marc Janaillac, Chief Executive Officer of Air France-KLM Group, attends a news conference in Paris, France, May 4, 2018. REUTERS/Charles Platiau

PARIS (Reuters) - Air France-KLM's AIRF.PA board will decide on a management transition plan on May 15, the company said on Saturday, after CEO Jean-Marc Janaillac said he would step down when staff at its French brand rejected a pay deal.

More than half of the staff at the French carrier who cast a ballot voted against the offer of a 7 percent salary increase over four years, prompting Janaillac to say he would resign.

Strikes over the pay dispute, due to resume on May 7 and May 8, have cost the company 300 million euros ($360 million) so far.

Janaillac, who is chairman at Air France as well as chairman and CEO of parent group Air France-KLM, agreed to stay on until a May 15 shareholder meeting, the company said in a statement. Air France-KLM’s board will also meet then.

($1 = 0.8363 euros)