Belgian artist Rene Magritte was the star of the night at Christie's auction of impressionist and modern art in London late on Wednesday, underlining the strong appetite for surrealist art among collectors.

While not the top lot in terms of value, Magritte's "Les jours gigantesques" painted in 1928 fetched 7.2 million pounds ($11.3 million), several times its pre-sale estimate of 800,000-1.5 million pounds and the second highest price for the artist at auction.

Christie's, the world's largest auctioneer, said the depiction of a woman and her attacker sparked a "fierce" bidding war between 10 people. The New York Times reported that the buyer was New York financier Wilbur Ross.

The most expensive work of the sale was Pablo Picasso's "Femme assise" (1949) which fetched 8.6 million pounds compared to expectations of 5.0-7.5 million.

Pre-sale estimates do not include buyer's premium, but final prices do. The commission to Christie's is 12 percent on everything above 500,000 pounds.

Another Picasso, "Femme au chien" (1962), raised 7.0 million pounds, towards the lower end of its pre-sale estimate, and Paul Signac's "La Corne d'or. Les Minarets", painted in 1907, sold for 6.2 million pounds.

One of the star lots of the night, a female nude by Pierre-Auguste Renoir entitled "Baigneuse", was withdrawn from the auction after a private deal was struck. It had been expected to raise 12-18 million pounds.

Overall the auction raised 92.5 million pounds ($145.5 million), compared with pre-sale expectations of 86.5-126.7 million.

While the final total falls short of the low estimate when commission is taken into account, the inclusion of the Renoir could well have lifted the sale to fall comfortably within range. Of the 70 lots on offer, 14 failed to sell.

On Tuesday, Christie's rival Sotheby's raised 75.0 million pounds at its equivalent auction, at the low end of expectations. Despite setting a new auction record for Joan Miro of 23.6 million pounds, the sale elsewhere was lackluster.

The two sales kick off three weeks of major auctions in London where up to $1 billion of art is on offer.

(Reporting by Mike Collett-White, editing by Paul Casciato)