Christie's International, the world's largest art seller, said its auction totals rose 36 percent last year to 2.5 billion pounds ($4.7 billion) as it sold a lion's share of expensive paintings by Gustav Klimt and other artists.

The U.S. was the fastest-growing market for London-based Christie's, which is owned by the French billionaire Francois Pinault. New York auctions totaled $2.1 billion, for a gain of 50 percent in U.K. pounds, the company said.

Christie's and its rival Sotheby's are benefiting from low interest rates and a 10-year trebling of contemporary prices that have made art an attractive investment for billionaires from Ronald Lauder in the U.S. to Hong Kong's Joseph Lau. Sellers have been lured with promises of benefits such as minimum prices.

"If you have the best works in your sales, the best buyers come to you,'' Christie's Chief Executive Officer Ed Dolman said in a telephone interview today. "It was a very good market, and we managed to grab most of it.''

Christie's didn't provide year-earlier figures for comparison, only percentage changes.

In November at Christie's, Lauder's Neue Galerie in New York bought Ernst Ludwig Kirchner's "Berlin Street Scene'' for a record $38.1 million, while selling other works. Andy Warhol values rose as Lau paid $17.4 million for a "Mao'' image; Forbes magazine has valued the singer Madonna's Wiltshire shooting estate at a similar amount.

Sotheby's Gain

Publicly traded Sotheby's sold $3.7 billion of art in 2006, up 36 percent from a year earlier, based on data gathered for analysts and investors. The world's second-largest auction house has a stock-market value of more than $2 billion.

Based on auction totals, Christie's might be valued at even more if it sold shares to the public, though the ideal moment for such a sale may have passed. Sotheby's shares' 52-week high was $38 on Oct. 31. Christie's isn't looking for outside funding, Dolman said today.

Christie's London auctions rose 24 percent, to $1.4 billion. U.K. growth was less than Hong Kong's, where art sales totaled $355 million, a 25 percent increase. French auctions jumped about 77 percent, to $248.9 million, Christie's said.

Among Christie's top pictures in New York, Klimt's portrait of the Vienna hostess Adele Bloch-Bauer fetched $87.9 million. A Willem de Kooning set a $27.1 million record for a postwar work. In art, as in the stock market, sellers are betting against buyers.

"When things are perceived to be very good, you do think seriously about selling,'' said Philip Hook, a senior director of impressionist and modern art at Sotheby's. "Who knows how long the boom will last?''

Picasso Painting

In the first half of 2006, Sotheby's wasn't far behind Christie's, thanks to a Pablo Picasso painting, "Dora Maar au Chat,'' offered by a relative of Chicago businessman Ron Gidwitz, which fetched $95.2 million in New York in May.

Christie's widened its lead in the second half partly by offering sellers more incentives such as promises of minimum prices. Christie's said it guaranteed about $165 million of November's impressionist and modern evening auction in New York. That included four Klimts owned by Nazi victims' heirs and a Picasso owned by Andrew Lloyd Webber's Foundation, which Christie's withdrew from the sale,

Even so, Christie's raised $491.5 million in a night, more than Christie's and Sotheby's sold last year in a week of winter auctions in London.

Christie's won most of the top lots for November's New York sales by forging relationships with sellers and promising incentives such as minimum prices, Dolman said.

Russian Buyers

The auction house sold $1.2 billion of impressionist and Modern art pictures in 2006, up 81 percent. Postwar and contemporary auctions rose 47 percent, to $822 million. The huge growth in the U.S. was fueled by new clients, particularly Russians, who visit the New York salerooms, Dolman said.

Private sales of art outside the auction rooms exceeded $256 million. In addition, Christie's advised the seller of a Klimt picture that Lauder bought for $135 million in June.

Sotheby's Chief Executive Officer William Ruprecht said last month his goal was profit, not market share. "We're not in the same game as Christie's,'' he said.

Publicly traded Sotheby's reports fourth quarter and full- year revenue and profit in March. Privately held Christie's doesn't disclose revenue or profit, though it reports auction totals twice a year.

This year's first big sales start on Feb. 5 in London, and may raise as much as $786 million from impressionist, modern and contemporary works, according to data supplied by the auction houses to Bloomberg.

Sotheby's high estimate for its auctions is $385.5 million and Christie's about $401 million. The London winter sales for the two houses in 2006 totaled $451 million, up from $322 million.

By Linda Sandler, Bloomberg