Anglo American (LON:AAL) said third-quarter copper production went up by nearly a third compared to the same period last year, reaching a quarterly record mainly thanks to improved performance at its Chile’s Collahuasi mine, a partnership with Glencore Xstrata (LON:GLEN).

Production of copper, the second-most important contributor to Anglo’s balance sheet after iron ore, rose 32% to 207,300 tonnes in the three months to September, above analysts’ expectations.

Collahuasi, located in Chile’s north, about 4,800 meters above sea level, more than doubled output to 63,600 tonnes in the three months.

Iron ore, however, came in significantly below expectations, putting Anglo at a disadvantage when compared to Rio Tinto’s (ASX, LON: RIO) record levels reported on Tuesday. Platinum remained about the same, at 623,000 ounces, despite the recent strike affecting Anglo American Platinum (Amplats).

Diamonds, meanwhile, saw production jump by more than a fifth to 7.7 million carats, as operations at Anglo's Jwaneng mine in Botswana were fully restored after a slope collapse last year. The company's mines in Canada, Snap Lake and Victor, also helped lift output thanks to their higher performance in the quarter.

CEO Mark Cutifani, who took over in April as Anglo’s head, has promised to increase the miner’s returns, as the company has underperformed compared to other major mining groups.