A rare sculpture of a young ballet dancer by French impressionist Edgar Degas fetched a record 13.3 million pounds ($18.8 million) on Tuesday, a record for the artist, auctioneer Sotheby's said.

Petite danseuse de quatorze ans,Edgar Degas

"Petite Danseuse de Quatorze Ans" was one of only a handful of bronze casts by the artist remaining in private hands and was sold to a private Asian buyer.

It had been expected to sell for up to 12 million pounds, although the final price did include a buyer's premium. According to Sotheby's, the previous auction record for a Degas sculpture was $12.3 million set at Sotheby's, New York, in 1999.

The lot was part of Sotheby's London sale of impressionist and modern art, which raised 32.6 million pounds overall versus pre-sale expectations of 40.6-55.6 million pounds.

The auction, watched closely in the art world for signs of further fallout from the global financial crisis, underlines experts' views that extremely rare pieces are holding up well in value, but overall the market is weakening.

Degas' figure of a girl, dated 1879-81, was originally made in wax using a wire structure for the body. Degas dressed the figure in real silk, tulle and gauze and a wig.

The sculpture, the only one to be exhibited during the artist's lifetime, was found in Degas' studio after his death in 1917 and cast in bronze from 1922.

Ballet dancers were a major inspiration for Degas, and a pastel and gouache representation sold for $37 million at Sotheby's in New York in November, a record for the artist.

The sculpture was offered by John Madejski, a British millionaire who is chairman of Reading soccer club.