Nov. 5 (Bloomberg) -- Copper prices declined as rising inventories fueled concern that demand is waning for the metal used in pipes and wires.

Stockpiles monitored by the London Metal Exchange jumped 1.5 percent to 379,825 metric tons today, the highest level since May 11 and the biggest advance in six weeks. The gain was “sizeable,” said Edward Meir, an analyst at MF Global Ltd. in Darien, Connecticut. Copper prices dropped 2.6 percent last week on concern that consumption may falter. Futures in New York have more than doubled this year.

“There’s some uncertainty about future demand,” said Patrick Chidley, an analyst at Barnard Jacobs Mellet LLC in New York. “People are seeing this as an opportunity to take some profit.”

Copper futures for December delivery fell 3.6 cents, or 1.2 percent, to $2.957 a pound on the Comex division of the New York Mercantile Exchange.

“We are still wary about metals,” Meir said in a report. Copper has “uninspiring fundamentals, typified by patchy demand and rising LME stocks,” he said.

Copper prices jumped this year after Chinese imports surged. Inventories at warehouses monitored by the Shanghai Futures Exchange have soared 62 percent since Aug. 1, raising concern that demand from the Asian nation is slowing.

Mine Strikes

Concern that supply is being constrained has “sustained prices at current levels, despite an expectation for a softening in Chinese import demand,” Nicholas Snowdon, an analyst at Barclays Capital in London, said in a report.

The combined annual capacity at copper mines where labor negotiations are being held this year is 1.2 million tons, said Daniel Major, an analyst at RBS Global Banking & Markets in London.

“There is potential strike action at Antamina, which could be supportive in coming days,” he said, referring to Cia. Minera Antamina SA. The Lima-based company runs the world’s largest combined copper and zinc mine.

Antamina, owned by BHP Billiton Ltd., Xstrata Plc, Teck Cominco Ltd. and Mitsubishi Corp., said yesterday it is interested in reaching a “reasonable agreement” with the workers union. The company said it has a “contingency” plan in case talks break down.

The mine is expected to produce 335,000 tons of copper this year, or 2.2 percent of global supply, according to RBS.

Copper for delivery in three months fell $44, or 0.7 percent, to $6,531 a metric ton ($2.96 a pound) on the LME.

Zinc, tin, lead and nickel prices also dropped in London. Aluminum was unchanged.

To contact the reporters on this story: Anna Stablum in London at astablum@bloomberg.net; Millie Munshi in New York at mmunshi@bloomberg.net.

Last Updated: November 5, 2009 15:21 EST