"There is a big cultural difference between France and England," said Mr Costes. "Everyone drinks a bit in France, but as part of a meal, not in order to get a buzz."  

"To do that, the young are turning to cannabis," he said.

A nationwide drink-driving awareness campaign and stricter controls have helped change drinking habits in favour of cannabis smoking.

"Today's young people who want to rebel don't want the 'old-fashioned' image associated with wine and alcohol," said Mr Costes.

"Unlike in the UK, binge-drinking is very uncommon - the French steer clear of hangovers or feeling ill."

"It takes them out of action for too long."

"Our studies show that they are turning to cannabis because its effects reinforce their state of mind without fundamentally altering it. They don't want to get wasted, and are still able to function and co-ordinate under its influence."

His report found that in 2005 about a quarter of French people and half of 17-year olds said they had tried cannabis. More than a million are regular users and half a million smoke a "joint" every day.

Among the young, the number of regular cannabis users is now almost the same as regular alcohol drinkers.

Breton youths leave the rest of France behind in consumption of cannabis, and the western region also comes top of the alcohol consumption league.

"We think this has something to do with the Celtic connection," said Mr Costes.

His findings also appeared to shatter the stereotype of the French leading a stress-free life with short working hours and plenty of holiday, as he pointed out that the French lead the world in the consumption of tranquillisers.

"There is a general rise in the amount of anti-depressants taken in France and the precursor to this in the young is cannabis, but that of course, is just my opinion," he said.

More interestingly perhaps, cocaine use has also doubled in the past five years, showing a disturbing trend of rising opiate drug abuse in France!

Part of the rise in drug use is due to falling prices, while the number of French who grow their own cannabis at home has risen to at least 200,000.