March 11 (Bloomberg) -- Copper prices gained on supply concerns after an earthquake struck Chile, the world's biggest source of the metal.

A magnitude 6.9 earthquake hit south of Santiago at about 9:40 a.m. New York time, the U.S. Geological Survey said today on its Web site. An 8.8-magnitude temblor, the world's fifth- strongest in a century, killed more than 400 people on Feb. 27, briefly shut mines and prompted a three-day copper rally. Aftershocks have rocked the country for the past two weeks.

"Copper rose as a knee-jerk reaction to the earthquake," said Frank McGhee, the head metals dealer at Integrated Brokerage LLC in Chicago. "The concern now is each time this happens, it causes an additional impact on roads and facilities. It creates an overall infrastructure problem."

Copper futures for May delivery rose 0.9 cent, or 0.3 percent, to $3.377 a pound on the Comex in New York. The most- active contract has advanced 2.8 percent since Feb. 26.

The metal added as much as 0.8 percent today after initial reports put the quake, about 90 miles (145 kilometers) southwest of Santiago in Libertador O'Higgins, at magnitude 7.2. The region, north of the Feb. 27 temblor's epicenter, was hit by three tremors above magnitude 6 in less than an hour today.

Chile's state-owned Codelco, the world's biggest copper producer, evacuated its Ventanas smelter on Chile's central coast after a tsunami warning. The Santiago-based company said there were no reports of problems at its El Teniente and Andina mines after the 6.9 quake, which shook buildings in the capital.

"It's a classic case of shoot first and ask questions later," said David Thurtell, an analyst at Citigroup Inc. in London. There is "always a risk that production might be affected," he said.

On the London Metal Exchange, copper for delivery in three months climbed $24, or 0.3 percent, to $7,464 a metric ton ($3.39 a pound). Zinc, nickel, tin and lead fell. Aluminum gained.