France's civil aviation authority has told airlines to ensure they have enough jet fuel as striking unions force shutdowns at refineries belonging to French oil major Total, an airport official said.

"The civil aviation authority's management has advised airlines to take steps to ensure jet fuel supplies," a spokeswoman at Nantes Airport said on Thursday.

She stressed that there had been no disruption to flights from that airport due to the strikes which have so far shut the Donges oil refinery in western France and threaten to close down four of the remaining five.

There were no immediate reports of fuel shortages at any of the country's provincial airports.

The workers are striking over a government law forcing them to give up the Pentecost public holiday to help fund health care for the elderly, and over wage demands.