PARIS - Britain on Wednesday warned its skiers and snowboarders to avoid excess alcohol when taking to France's ski slopes, after a spate of drink-related deaths and serious accidents.

More than thirty Britons died in Alpine accidents last year, half of whom were under 25. Many died because they underestimated the risk of drinking at a high altitude, British diplomats in the French city of Lyon said.

"Over the past years, we've noticed a rise in accidents in resorts linked to alcohol consumption, particularly accidents on the slopes, mostly among young people," British ambassador Peter Westmacott told reporters when launching an anti-drink campaign.

"We are telling our compatriots to be careful: when you consume too much alcohol at an altitude and it's cold, the danger is greater," he said.

The effects of alcohol are magnified by higher altitudes.

The campaign poster carries the slogan "Don't catch your death" and shows young drinkers, glass in hand, before an Alpine background.

French authorities said drink-skiing was becoming a growing problem in resorts and had caused several accidents on the slopes in recent winters, including avalanches set off by tipsy tourists going off-piste.

A study published by the British foreign ministry estimated a third of skiers and snow-boarders under 25 had experienced problems abroad linked to a mix of altitude, adrenaline and alcohol.

Westmacott said the embassy had often been forced to bear the cost of accidents since many British tourists failed to take out appropriate insurance covering winter sports.

The campaign posters will be put up at French airports and in resorts, and there will also be an online campaign.

Some 700,000 Britons visited French ski resorts last winter, Claire Bouteille, Britain's consul in Lyon said. An increase in low-cost flights to Lyon has helped fuel British tourism in the Alps.