A life-size bronze sculpture by Henri Matisse, which has never been sold at auction, is expected to be the star of the autumn art sales and could fetch up to $35 million, art experts said.

Matisse's "Back IV (Nu de Dos, 4eme etat)," circa 1930 is being sold at Christie's on November 3 by a private European collector, whom the auction house declined to name.

But Christie's said the owner recognizes the tremendous market opportunity for modern sculpture at this time.

"Conceived on an epic scale, Back IV is a powerfully reductive expression of the human form that stands as a milestone in the evolution of modernist style," said Conor Jordan, the head of Impressionist and Modern Art for Christie's Americas.

Another life-size sculpture, Alberto Giacometti's "Walking Man I," briefly became the most expensive work ever auctioned in February when it sold for more than $104 million.

Another Giacometti and a sculpture by Amedeo Modigliani each sold for more than $50 million this year.

Christie's is expected to announce the Matisse sale publicly this week.

The Matisse work is the last of a series of four sculptures that Jordan described as Matisse's most ambitious project, which the artist worked on for more than 20 years.

Twelve bronzes were produced of each piece in the series.

"As our upcoming sale represents the first time that any of the Back sculptures has ever been offered at auction, we expect tremendous enthusiasm from collectors around the world who will recognize this superb bronze as one of the most important sculptural achievements of the 20th century," he explained.

Apart from its rarity, intense interest in the sale is expected following the enthusiastic response to the "Matisse: Radical Invention" exhibit at the Museum of Modern Art (MOMA) which is ending soon.

All four of its "Back" sculptures were moved from MOMA's sculpture garden to its galleries, where they were among the show's focal points.

In May Christie's sold the most expensive work ever auctioned, Pablo Picasso's "Nude, green leaves and bust" which fetched $106.5 million -- just days after a landmark Picasso exhibition opened at the Metropolitan Museum of Art.

"We have witnessed great strength at the top end of the market, particularly where superlative examples of modern sculpture are involved," said Marc Porter, chairman of Christie's Americas.

Among the 12 "Back IV" works produced, all but two are in museum collections including MOMA, London's Tate Modern and the Pompidou Center in Paris.