Alain Ducasse, recently voted the best chef in the world, has bowed to the growing liking of the French for the unFrench habit of taking a quick, open-air lunch.

M. Ducasse, 46, the only chef to have two three-star restaurants in the Michelin guide, has turned his gastronomic talents to the takeaway meal, in the form of the haute cuisine lunch-box and the three-star pique-nique.

A grocery and sandwich shop M. Ducasse started in Paris last year with a celebrity baker, Eric Kayser, is offering three picnic menus from €21 (£15) each. There are also simpler lunch-box meals, a sandwich, a drink and a dessert, at €12 each.

M. Ducasse, known for his entrepreneurial skills as much as his flair in the kitchen, is bowing to the inevitable.

The sandwich shop, or takeaway food of any kind, was once regarded as a betrayal of the French way of life. Parisian parks, the quays of the Seine, even the bridges over the river, are now crowded on fine days with people eating simple or elaborate meals in the open air.

French department stores say picnic paraphernalia - from plastic knives to wicker hampers with all the trimmings - is among the fastest-selling lines this summer.

The champagne house Veuve-Cliquot spotted the trend last year, producing mini-bottles of champagne with small orange holders, intended to be drunk, elegantly, straight from the bottle en plein air.

Although the long and detailed Parisian lunch is not entirely dead, more and more French city-dwellers take their mid-day food on the run or on a bench or in the park.

The bible of French social habits, Francoscopie, reported this year that one in three French people now eats lunch without going near a table.

Four in 10 admit occasionally eating in the street. One in three frequently eats in the office or work-place.

A growing trend is for groups of friends who used to meet in a favourite restaurant to arrange to share food at a picnic in the park.

Julien, 25, who meets friends on the Seine quays or in the Esplanade des Invalides, said: "We send an e-mail with the time and location to the whole group. Anyone who wants to can come along."

This is, in a sense, a revival of a French tradition older than the long restaurant lunch. The word picnic, or pique-nique, is said to originate in an 18th-century rural habit of communal meals; each person brought a dish and everyone took what they wanted.

M. Ducasse, who has the three-star restaurants in Monaco and Paris, a brasserie in Paris, a haute-cuisine restaurant, and soon a brasserie in New York, is head of a €16m-a-year business.

His three-star picnics are aimed at those people who wish to maintain high gastronomic standards, even if they are eating in the open air. His shop Boulangépicier, jointly operated with Mr Kayser at 73 Boulevard de Courcelles in the eighth arrondissement of the French capital, is conveniently close to the beautiful Parc de Monceau.

It offers three picnic menus, "light", classique and gourmand (which technically means greedy but has no negative connotations in modern French).

The gourmand menu might consist of nutted bread with ham and a marmelade of cèpe, mushrooms, a shellfish salad, fresh fruit, crisps and a biscuit and a choice of wine or soft drinks.

A "light" menu might offer soft-boiled eggs with a minced tomato sauce, smoked tuna and a lettuce heart and mango salad.

For the less hungry, or less wealthy, the shop offers a €12 lunch-box, containing a sandwich on speciality bread, a drink and a dessert.