Workers at French nuclear power stations are due to down tools amid growing industrial action over controversial labour reforms.
The CGT union said staff at 16 of France’s 19 nuclear plants had voted for a one-day strike.
Petrol is already in short supply after days of strikes, and nuclear power stations were reducing operations ahead of Thursday’s action.
Prime Minister Manuel Valls has indicated he could modify the labour laws but the reforms would not be withdrawn.
There have been long queues at petrol stations as strikes and blockades disrupting six of France’s eight oil refineries affected supplies.