Air France KLM shares slumped on Monday after the company’s chief executive said he would resign following the rejection of a pay deal by the airline’s staff continuing their industrial action in pursuit of a 5.1% pay rise.

A series of Air France strikes—13 one-day walkouts so far in recent weeks—have cost the company at least €300 million ($359 million). Meanwhile, Monday’s strike prompted the cancellation of about 15 percent of Air France flights worldwide.

Air France employees were given an opportunity to express their opinion on the multi-year pay proposal. Thus, Air France reported that the vote period came to an end on 4 May, 2018.

With a participation rate of 80.33%, 55.44% of employees voted “no”. 

“As a result, the pay agreement proposal of April 16 ensuring a 7% wage increase over 4 years, including a 2% increase in 2018, is no longer valid,” the company said, and Air France-KLM CEO Jean-Marc Janaillac is following through on his promise to be personally accountable.

The French government owns 14.3% of the Air France-KLM parent group. Correspondingly, on Sunday, minister Bruno Le Maire warned Air France could “disappear”.