Schools will shut, business activity will slow and aperitifs will flow in sun-soaked gardens today while the French confirm their status as the world holiday champions with an unofficial day off.

Ignoring the call from President Sarkozy to work harder, millions of employees will down tools to travel to the seaside and the countryside on what is, in theory, an ordinary working day.

The upshot was two-hour traffic jams around Paris last night as residents headed out of the city, a 30 per cent fall in production for many industries and a rise of up to 20 per cent in holiday bookings compared to last year. Absenteeism will be rife among school pupils. But they are unlikely to be punished because many of their teachers are also playing truant.

The national lie-in has been made possible by a calendar that placed the VE-Day Bank Holiday yesterday, May 8, and the Whit Monday Bank Holiday on May 12. By staying away from work today, the French get a five-day break. A day off squeezed between Bank Holidays is known as le pont (the bridge), and many companies will see up to 90 per cent of their workers on it. Some businesses have shut altogether.

An opinion poll found that half of all French employees were planning to go away for either le pont today or the one last Friday after the May Day Bank Holiday. The survey underestimated the total number taking a day off because it did not include those who will stay at home.

Many staff have gone the whole hog and taken two weeks' holiday, to turn the month of May into what one executive described as an early August.

Mr Sarkozy has been criticised for spending too much time with Carla, his new wife, but the couple will miss out on the five-day weekend. The President led commemorations for VE-Day yesterday and will preside tomorrow over a ceremony to mark the end of slavery in France.

Marc Lestrohan, a director of Lauden, an electronics company in Brittany, said that 40 employees would be present today out of a total of 400. He said he would shut the machines down “because the cost of keeping them running would have been too high”. Talan, a consultancy, said that the cost of le pont to its sales could be as much as €300,000 (£236,000). Mehdi Houas, its chairman, said: “When we lose €150,000, the State loses €100,000 in taxes.”

But the National Institute of Statistics and Economic Studies dismissed qualms that the extended break could topple France's already wobbling economy. If employees were forced to work today they would merely take a holiday at another date, it said. So overall impact was limited.

Supporters of Mr Sarkozy disagree. They say the Gallic economy has fallen behind the British largely because the French take 11 days' more holiday a year, with each day costing about €1.8billion. If the French worked as much the British, they would add about 1 per cent to national wealth, according to advisers to the president. Mr Sarkozy has tried to encourage them to put in longer hours by abolishing income tax on overtime pay. Jacques Chirac, his predecessor, sought to do the same by ending the Whit Monday holiday.

Neither scheme has worked. The Whit Monday holiday has been reinstated after union protests and there are no signs of an increase in overtime. A study last month found that the French remain the world champions of holidays, with a total of 37 days a year, against 27 in Germany and 26 in Britain.

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