Christie's auction house says a painting by Francis Bacon has sold for 17.96 million pounds ($28.7 million) at a sale in London.

Christie's says the 1953 oil painting, "Study for a Portrait," became the second most valuable piece to be sold at its postwar and contemporary art auctions in London.

It says the highest selling work in this category was Bacon's "Triptych 1974-77" which sold for 26.3 million pounds in February 2008.

"Study for a Portrait" came to an auction for the first time Tuesday from a private vendor, who had owned it since 1984. It was initially estimated to fetch about 11 million pounds.

The painting was sold to an anonymous telephone bidder. The auction price includes the buyer's premium.