(Bloomberg News) A pink "sponge" painting by the French conceptual artist Yves Klein sold tonight at an auction in London for a record 23.6 million pounds ($36.7 million) as billionaires once again battled for exceptional works by the most lauded names of postwar and 20th-century art.

The 1960 painted relief "Le Rose du bleu (RE 22)," encrusted with nine sea sponges, had been valued by Christie's International at 17 million pounds to 20 million pounds in its 69-lot sale. It was won by a telephone bid taken by Francis Outred, Christie's European head of contemporary art, underbid by an unidentified woman in the room and at least one other telephone bidder.

Entered from an unidentified private collection, it was one of the earliest of just 12 such sponge reliefs that the artist executed in pink, rather than his trademark ultramarine blue, and had had never been offered at auction before, according to the Christie's catalog.

The owner had been encouraged to sell by the record $36.5 million paid for Klein's 1962 work, "FC1 (Fire Color 1)," at Christie's, New York, in May. Prices for Klein have risen in recent years as international collectors have become aware values of influential post-war European artists have lagged behind those of their U.S. equivalents.

The Klein was one of six lots in the auction that were guaranteed to sell either through third-party finance or an advance from Christie's to the vendor.

Richter Abstract

Seven lots later, a 1989 abstract by the German artist Gerhard Richter sold for 12.7 million pounds.

The large oil on canvas, titled "Strukture (2)," painted in shades of white, black and red using a squeegee, was another guaranteed work fresh to the auction market. Estimated at 9 million pounds to 12 million pounds and also guaranteed, it was bought by Brett Gorvy of Christie's, taking instructions on the telephone and underbid by another prospective telephone bidder.

Richter has been on a bull run at contemporary art auctions since a Sotheby's auction in November in New York, when a group of eight of his abstracts all sold above their upper estimates.

Christie's achieved another record for the Cologne-based artist when $21.8 million was paid for the 1993 painting, "Abstraktes Bild (798-3)" in New York in May. A 1986 Richter abstract with an asking price of $20 million-$25 million was sold earlier this month by the New York-based Pace Gallery at the Art Basel fair.

Richter's average sale price reached $3.1 million in 2012 from $290,112 in 2009, according to Artnet.

Record Estimate

The 69 lots are estimated to raise between 102.6 million pounds and 139 million pounds, a record for a contemporary-art sale at the London-based auction house.

The event is part of a series of auctions at Christie's, Sotheby's and Phillips de Pury & Co. in the U.K. capital that offer more than 1,000 works by established and emerging artists, carrying a total value of as much as 290 million pounds. They follow the Art Basel fair in Switzerland this month and Sotheby's 41.4 million-pound auction of the Gunter Sachs collection in London on May 22-23.

The 1964 Francis Bacon oil "Study for Self-Portrait" found a buyer at 21.5 million pounds after being given an unpublished valuation of 15 million pounds to 20 million pounds.

The painting had been previously offered by Christie's in New York in November 2008, when the market was hit by the financial crisis. It failed to sell. The work subsequently became the subject of a lawsuit filed in March 2009 in the U.S. District Court in Manhattan between the auction house and a family trust led by the Connecticut collector George A. Weiss. The trust claimed Christie's hadn't honored the promise of a $40-million guarantee.

The case was settled out of court last year. Since then, research has shown that the painting combines Bacon's face with a body based on a John Deakin photograph of the artist's friend Lucian Freud.

Listed in the catalog as being the property of a private New York collector, the painting was guaranteed by the auction house, rather than a third-party, Christie's said.

It was bought by art dealer Christophe Van de Weghe, bidding in the room, underbid by gallery owner William Acquavella.

A trademark self-portrait by Jean-Michel Basquiat sold for a record 12.9 million pounds with fees. The 1981 canvas "Untitled," showing the former graffiti artist with hands raised beside his mask-like face, is acrylic, oilstick and spray-paint.

Christie's painting was being entered by a collector based on the West Coast of the U.S. who bought it for a record $14.6 million at auction in 2007. The work had been sold by the Israel Museum, Jerusalem. At the time, the price was about three times the previous high for Basquiat, said Brett Gorvy, Christie's chairman and international head of postwar and contemporary art, who was the winning bidder for a telephone client tonight.