
French oil workers have voted to continue the strike, which has led to shortages at petrol stations across the country.
They hit back with anger after the Government said it would use enforcement powers to force some of them back to work.
The strike, now in its third week, has shut down six of France's seven oil refineries.
With long queues of cars now a regular sight at gas stations, the government is calling for an end to the strike.
Almost a third of gas stations are now reported to be out of at least one type of motor fuel.
Unions want wage increases for their workers, which they say should take into account the huge profits that oil companies are making at the moment.
They are asking for a 10 percent pay rise – 7 percent to cover inflation and 3 percent for what they call "wealth sharing."
The government's latest move to avoid the impact of the crackdown is to seek out key personnel at a refinery in Normandy, threatening prosecution if they don't allow some tanker trucks to fill up.
French Prime Minister Elisabeth Borne said that if no agreement could be reached between oil firms and unions, the government would act to "unblock the situation".
But hard-left unions behind the bans see it as a threat to their right to strike and have hardened their position, calling the government's warning "illegal" and an "option of violence".
A spokesman for the CGT union said it was awaiting government notices and would challenge them in court.
On Friday, French President Emmanuel Macron called on unions to end the strikes, but said energy companies must listen to workers' "legitimate wage demands".
The strike action has divided opinion in France, with some commuters expressing anger at fuel shortages and stressing that they need their cars for work.
But at a time of growing anxiety about the cost of living and rising profits for some energy companies, others have expressed sympathy for the strikers.