Air France pilots have voted to extend their week-long strike over plans to expand low-cost operations abroad.

Of three-quarters of pilots from the SNPL union who cast their ballot, more than 80 percent agreed to continue industrial action beyond Monday’s deadline, according to Jean-Louis Barber, head of the union’s Air France section.

Only 38 percent of flights are expected to be assured on Sunday, the lowest proportion since the strike began. Saturday has seen 45 percent of flights confirmed.

Pilots are protesting against plans by Air France to fight competition from low-budget carriers and boost earnings by setting up foreign bases for its low-cost Transavia brand.

The main pilots’ union fears the airline may abandon Transavia’s development in France altogether and move jobs out of the country.

Air France has condemned the move to continue the strike, insisting neither the airline nor its staff will be harmed by its plans.

It says the strike is costing the company 10-15 million euros a day.

Air France adds that flights operated by other airlines, including HOP, KLM and Delta, are not affected by the strike.