Christie’s International said sales of art and collectibles rose to a record 2.7 billion pounds ($4.6 billion) in the first six months of the year as purchases of contemporary works and demand from new clients surged.

The tally at London-based Christie’s, the world’s largest art broker, increased 12 percent from the same period in 2013 as 52 works fetched more than $10 million and 479 lots exceeded $1 million, the company said today in a statement.

A growing population of wealthy individuals is spending more on art, particularly for contemporary works that are seen as strong investments. New clients represented 24 percent of all buyers in the first half as the auction house expanded in Hong Kong and China. Sales to clients in Asia accounted for 28 percent of the activity, and 20 percent of new clients were based in Asia.

“This demand is evidence that we’re living in extraordinary times,” Steven Murphy, Christie’s chief executive officer, said in a phone interview. “There’s an increase in the buyer pool and that has increased prices. The success of the sales is bringing more great art into the market. Our clients are buying art they love and want.”

Postwar and contemporary art sales of 799.9 million pounds, with fees, rose 20 percent from a year earlier. The May evening sale in New York fetched $744.9 million, an auction industry record. The top lot Christie’s sold in the past six months was Barnett Newman’s “Black Fire I,” which went for $84.2 million during the New York May sale, an artist record. The second- highest lot was Francis Bacon’s triptych “Three Studies for a Portrait of John Edwards,” which sold for $80.8 million at the same event.

Online Auctions

Online auctions continue to gain in popularity, as sales of 8.7 million pounds surged 71 percent from the first half of 2013, Christie’s said. About 27 percent of online buyers were new. The top price on the Web was $905,000 for the Richard Serra painting “Pamuk,” offered during the May sales.

“We’re tapping into a market that was latent,” Murphy said. “We’re engaging with an interest that was already out there.”

Sotheby’s, the auction house that put activist investor Dan Loeb on its board after he battled with management over performance and strategy, said this week it entered into a partnership with EBay Inc. to sell artworks online. The companies are building a platform for collectors and first-time buyers to browse and purchase items including art, jewelry and fine wine, according to a statement. EBay and Sotheby’s will start with live auctions at New York-based Sotheby’s.

‘Good’ Competition

Internet bidders competed for 17 percent of the lots offered in 2013 by Sotheby’s, which in April sold John James Audubon’s “The Birds of America” for an online record price of $3.5 million.

“More online activity is a good thing even if it’s from the competition,” Murphy said of the Sotheby’s-EBay pact, adding that Christie’s has spent $50 million in the past three years building its online platform. He said the auction house wouldn’t rule out a partnership with an online business, adding, “we’re pleased with our progress and our success speaks for itself.”

Christie’s is a closely held company owned by the French billionaire Francois Pinault. The auction house was acquired by Pinault’s holding company, Artemis SA, for $1.2 billion in 1998. Christie’s, which doesn’t report revenue or profit, releases sale totals twice a year.

Impressionist and modern art, the big money-makers for the auction houses during the 1980s, were Christie’s second-most lucrative auction category, as sales of 565.9 million pounds climbed 37 percent from the first half of 2013.

Asian Art

Asian artwork sales of 222.7 million pounds were down 22 percent. Murphy called that a “dip” rather than a trend for the category, saying full-year results will be more telling.

Christie’s said it’s opening a sales room in Shanghai in October to coincide with auctions of Asian and Western 20th century and contemporary art, jewelry, watches and wine. The company is expanding its New York location at Rockefeller Plaza, with 11,000-square feet of galleries opening in November to display art slated for private sale.