Chilean mining company Codelco, the world's largest copper producer, said Tuesday work has halted at one its main mines because of a week-old strike by contract workers.

Because of picketers outside the facility the company had trouble during a shift change at the Chuquicamata mine and production has stopped, the company's executive president Nelson Pizarro said.

Workers employed by subcontractors hired by Codelco have been on strike for a week to demand higher wages.

"We hope to resume operations quickly but that is going to depend on our being able to get through the gates," Pizarro told reporters.

Chuquicamata, located 1,650 kilometers (1,000 miles) north of Santiago, produces around 339,000 tons of copper per year, making it one of the company's most productive mines.

Codelco's produces 11 percent of the world's copper.

The stoppage at Chuquicamata follows similar action at a mine called Division El Salvador, one of the company's least productive with 54,000 tons a year.

The striking workers have blocked access roads and scuffled with police.

Last Friday a worker at the El Salvador mine died after being shot by police trying to clear a road blocked by picketers.

The company says it cannot afford a raise for the contract workers because copper prices are at their lowest level in six years amid sluggishness in the global economy.