A spokesperson for operator TotalEnergies said that, with shipments from depots and refineries blocked, production would need to be stopped once maximum stock levels had been reached.

"This will be done on a unit-by-unit basis," the spokesperson said.

Fuel deliveries are currently being prevented from leaving the company's La Mede biorefinery in southern France, while its Donges refinery in the west has been offline due to a technical problem with an electricity transformer, the spokesperson said.

Operations were normal at the company's Normandy site in the north, while the Feyzin refinery in the southeast was operating almost normally, the person added.

A union official said earlier that the Normandy refinery would be stopped this weekend.

At oil major ExxonMobil's Esso-branded Port Jerome refinery in Normandy, workers have been called to strike from Saturday at 2 p.m. (1300 GMT), a CGT union official said.

It was unclear whether Esso's Fos-sur-Mer refinery in the south would be similarly affected. An ExxonMobil spokesperson did not immediately respond to a request for comment.

A spokesperson for the Lavera refinery in southern France operated by PetroIneos said on Friday it had had no notification from unions about planned stoppages on Monday, and was unable to give details on crude stock levels.

(Reporting by Benjamin Mallet, Forrest Crellin and America Hernandez; Editing by Jan Harvey and Mark Potter)

By America Hernandez and Forrest Crellin