Nov. 2 (Bloomberg) -- Monterrico Metals Plc, a U.K. mining company operating in Peru, said unidentified gunmen attacked its copper project in the nation, killing at least two workers.

About 20 men armed with rifles and revolvers burned the workers camp at the Rio Blanco deposit in the northern Andes yesterday and shot dead two of the guards, the mine’s manager Wu Jian told Lima-based Radioprogramas today. Seven additional workers are missing, he said.

“No one knows exactly what happened, but the camp has been completely destroyed,” Wu said. “We only know that two of our workers are dead.”

Protesters opposing pollution attacked the mine at least three times since 2005. The $1.5 billion Rio Blanco project, with 1.26 billion tons of copper resources, could produce 220,000 tons of copper a year, a company study has said. The company intended to start production at the site in 2011.

A police helicopter is traveling to the site, 800 kilometers (500 miles) north of Lima, Interior Minister Octavio Salazar told reporters today in the Peruvian capital.

Wu and spokesman Andrew Bristow weren’t immediately available for comment today when contacted by Bloomberg News.

China’s Zijin Mining Group Co. holds a 79.9 percent stake in the deposit and LS-Nikko Copper Inc. has 10 percent.

Peru is the world’s third-largest copper producer.

To contact the reporter for this story: Alex Emery in Lima at aemery1@bloomberg.net.

Last Updated: November 2, 2009 11:52 EST