London auction houses Christie's and Sotheby's celebrated Friday a record week of modern art sales, with a Francis Bacon painting crowning deals worth nearly $800 million.

By the final tally Friday, buyers at both auction houses had spent £398.3 million ($777 million)—an unheralded sum for Europe and one nearing the heights of New York.

"A crazy market!" a Parisian art merchant exclaimed after emerging from Christie's empty-handed because of the skyrocketing prices.

Several artists saw their stars rise sharply this week.

Christie's on Feb. 8 auctioned a Francis Bacon painting belonging to Sophia Loren for the record price of £14.2 million ($27.5 million). The sale price makes it the most expensive work of art ever by Bacon, and a record price for a painting in the post-war period in U.S. dollars, though not in pounds—an effect of modern exchange rates.

Study for a Portrait II was estimated to sell for £12 million, the highest estimate of any work in a bumper crop of auctions this week by Christie's and rival Sotheby's.

The painting benefited from a touch of extra glamour because the seller was, according to specialists, the actress Sophia Loren whose late husband Carlo Ponti was a major collector.

The Feb. 8 sale beat the previous record sale for a painting by Bacon, who died in 1992, set by Version Nr2 of lying figure with hypodermic syringe, which sold for $15 million at a Christie's auction in New York last November.

The previous record for a post-war painting was set by Willem de Kooning's Untitled, which sold for $27.1 million, also in November.

A number of acrylics by Andy Warhol also changed hands for several million pounds last week. A portrait of Brigitte Bardot, painted in 1974 and which was expected to sell for between £1.5 and 2 million, was eventually auctioned for more than double that—£5.39 million.

Among the other major sales on Thursday was Untitled (Black, Red, Black on Brown) by Rothko, which was estimated to sell for between £1 and 1.5 million pounds, and auctioned for £3 million.

L'homme au foulard rouge, by Chaim Soutine, went Monday for £8.75 million, or twice the initial estimate, highlighting the appetite for Russian works.

The Cubist-inspired Les maisons dans les arbres, by Fernand Leger, surpassed all expectations when it sold for £6.3 million.

A canvas painted in 2006 by Damian Hirst, entitled Isopropamide Idiodide fetched more than £400,000.

Peter Doig saw his White Canoe go for £5.7 million, or five times its initial estimate.

Jussi Pyllkanen, an auctioneer who is president of Christie's Europe, said the auction house's efforts paid off for modern, impressionist and surrealist art.

"Christie's extensive work in the new market of Russian, Asian, and the Middle East saw tremendous competition brought to the sale," Pyllkanen said in a statement. "Clearly the art market moves from strength to strength and buyers from all over the world compete with confidence for major objects.”

By Lucie Godeau, copyright 2007 Agence France-Presse