(Adds statement from Cerro Verde, Freeport McMoRan, output details)
LIMA, March 6 (Reuters) - Workers at Cerro Verde mine, one of the largest copper producers in Peru, plan to start a five-day strike on Friday to demand better labor conditions, a union representative said on Monday.
The representative and the mine's controlling owners said the strike could be indefinite.
Cerro Verde is controlled by Freeport-McMoRan Inc , which owns a 53.56 percent stake. Sumitomo Metal Mining Company Ltd controls a 21 percent stake and Buenaventura 19.58 percent.
News of the Cerro Verde strike comes as output at the world's two biggest copper mines has been interrupted. Some 2,500 unionized workers at BHP Billiton's Escondida copper mine in Chile began a strike on Feb. 9 while Freeport's Grasberg mine in Indonesia has stopped due to a dispute over export rights.
Supply disruptions pushed copper prices to 20-month highs of $6,204 a tonne on the London Metal Exchange last month. Prices have come off these peaks since and were last trading at $5,851.50 a tonne.
The Cerro Verde union's deputy secretary, Cesar Fernandez, said workers wanted family health benefits and other measures and had not ruled out an indefinite strike. He said the mine's standards for sharing conventional profits with workers were too high.
A representative of Cerro Verde said the mine would continue abiding by the collective agreement it had forged with workers.
Cerro Verde produced 1.1 billion pounds (498,951 tonnes) of copper in all of 2016, more than double output in 2015 thanks to a recent expansion.
Freeport McMoRan said in a statement to Reuters it had been notified on March 2 the miners intended to go on strike for an indefinite period starting on March 10.
The company said Cerro Verde strictly complies with its obligations by law and under its agreements with the union, paying out amounts owed for conventional profits as required, and providing competitive vacation and healthcare benefits. (Reporting by Ursula Scollo; Additional reporting by Nicole Mordant in Vancouver; Writing by Caroline Stauffer; Editing by Chizu Nomiyama and Matthew Lewis)