LIMA: Workers at a US-owned copper mine in Peru launched a wage strike on Friday, heightening pressure on the market for the key commodity already hit by a similar stoppage in Chile. Some 1,200 workers downed tools at the southern Cerro Verde mine, majority-owned by Arizona-based Freeport-McMoran, said union spokesman Rommel Arias. The miners are demanding special benefit payments to protect their incomes against a downturn in copper prices, and better working conditions. “We have ended discussions with the company and no agreement has been reached,” Arias told AFP, “The strike starts at 7:30 am on Friday morning (1230 GMT).” Mining sector consultant Jorge Manco calculates that production at Cerro Verde reached half a million tonnes last year, making it Peru’s biggest copper mine. Strikes at copper mines have raised concerns on international markets for the metal, a key component in electrical wiring. Some 2,500 workers at the world’s biggest copper mine, the Escondida site in Chile, have been on strike for a month for higher pay. Analysts at British bank Barclays said Thursday that prices were stable despite the Chilean strike, since the world’s biggest copper consumer, China, is well stocked. Italian bank Unicredit meanwhile calculated that prices were falling slightly “with no end in sight” to the Escondida dispute.