SANTIAGO, Chile - Xstrata Plc said a build-up in copper stocks, responsible for the metal's worst first quarter in a decade, will end in "the next couple of months" as buyers return to the marketplace.

Chinese demand may recover to grow 6 percent this year, Charlie Sartain, who runs the Zug, Switzerland-based company's copper business, said in Santiago on Monday. Demand is also recovering in Europe and the United States, he said.

Xstrata will become the world's largest producer of copper concentrate by 2014 when its Las Bambas mine in Peru starts production, Sartain said. Copper fell 1.8 percent in the first quarter, the biggest decline for the period since 2001, as Chinese buyers consumed existing stockpiles and the country boosted copper scrap imports.