PARIS, July 30, 2008 (AFP) - Expected to fetch at least 300 million euro (almost half a billion dollars), an art collection amassed over four decades by late fashion king Yves Saint Laurent and his companion Pierre Berge goes up for sale next February.

A sign on the front door of the NYC Yves Saint Laurent store after his death in June 2008 - Photo : Stan Honda/AFP

Neither Christie's nor Berge's own auction house, Pierre Berge et Associes, would provide information on the sale, saying details would be released in September.

But art market sources described the auction as "the sale of the century" and estimated value at up to 500 million euro (778 million dollars).

Among some 600 masterpieces to go on sale are works by Picasso, Toulouse-Lautrec, Matisse or Leger that graced the pair's separate Paris homes, including a Mondrian that once belonged to Otto Preminger.

"I don't have confidence in the after-world," Berge told Le Figaro newspaper. "I prefer to organise things while still alive, which Yves might not have done. I could only organise this sale after his death. A page is turned."

Saint Laurent died June 1.

Well-known for their mutual passion for art, the pair collected the finest of oils, furniture, statuettes, enamels and jewellery.

Berge, who was several years YSL's senior and will turn 78 in November, frequented the likes of Paris literati Jean Giono and Jean Cocteau as a young man, and lived with Bernard Buffet before meeting Saint Laurent and setting up the YSL fashion empire.

In later years he ran a theatre, staged concerts, headed the Paris Opera, worked as a UNESCO goodwill ambassador and helped Chinese pro-democracy protesters after the events of Tiananmen.

Among pieces owned by the pair are Brancusi sculpture once owned by Leger, a marble bust from 100 AD, Renaissance enamels formerly the property of Count Stroganov, then Hubert de Givenchy, a tiny portrait of Louis XIV circled by 78 diamonds, a Goya, an Ingres, and 18th-century Chinese bronzes.