Jan. 14 (Bloomberg) -- Copper prices dropped after a report showed sales at U.S. retailers unexpectedly fell in December, curbing optimism that economic growth is accelerating.

Sales dropped 0.3 percent last month, the Commerce Department said today. Economists were expecting a 0.5 percent gain, the median of 80 estimates in a Bloomberg survey. Copper prices tumbled a record 54 percent in 2008 as a recession slashed demand.

"The retail numbers weren't very good," said Matthew Zeman, a trader at LaSalle Futures Group in Chicago.

Copper futures for March delivery fell 1.25 cents, or 0.4 percent, to $3.3875 a pound on the Comex division of the New York Mercantile Exchange. The price has more than doubled in the past 12 months.

Earlier, the metal gained as much as 1.3 percent on speculation that demand will increase in China, the world's biggest metal user.

"We were down a little today, but people will continue to buy on the dips," Zeman said. "People are generally feeling optimistic about growth in China, and buyers will jump in at lower prices."

China's imports of unwrought copper and products jumped 27 percent last month from November, government data show. An expanding economy will spur "ongoing robust demand" for metals from emerging markets, Goldman Sachs Group Inc. said yesterday in a report.

"All the focus is on China and the anticipation that we'll see stronger growth there," said Frank McGhee, the head dealer at Integrated Brokerage Services LLC in Chicago.

On the London Metal Exchange, copper for delivery in three months was little changed at $7,490 a ton ($3.40 a pound).

Aluminum, lead, tin and zinc rose in London. Nickel was unchanged.