Britons heading to France over the half term are being warned to prepare for possible fuel shortages as industrial action and panic buying leave an estimated 25% of petrol stations closed or running short on supplies. Motorists are having to queue for hours in some areas to fill up their tanks.

The industrial action was called by France's CGT union federation in protest at the planned introduction of new labour laws which would make it easier for firms to hire and fire workers and have more leeway over holiday pay. With an unemployment rate of around 10% the government hopes cutting back on red tape will encourage firms to hire more people, but unions say it will increase job insecurity and reduce the rights of workers and must be scrapped.

The dispute has already seen France dip into its strategic oil reserves for the first time in six years, with three days' supplies used from a total of 115 in reserve. There are fears the strike could worsen if employees at nuclear power stations and the transport networks join in. The country's gas reserves are also expected to be targeted.

With the Euros due to be held in France in just over a fortnight, there are fears the continuing crisis could affect the tournament — which would be deeply embarrassing for the government. However its attempt to end the crisis ended in failure after sending riot police to break up a picket at a refinery near Marseilles. The unions immediately called for strikes at all eight refineries nationwide.

In a statement the Foreign and Commonwealth Office (FCO) said: ":Following industrial action (blockades of fuel depots), fuel purchasing restrictions have been put in place by local authorities in some parts of France. In certain areas you may not be able to fill up jerrycans, and fuel rationing may be imposed. Some petrol stations may have run out of some types of fuel."