Aussie mining giant Rio Tinto's copper output uncertain for 2017

Aussie mining company Rio Tinto has been hit by a lower-than-expected performance at key copper mines in 2016, muddying the waters on their outlook for 2017.

The annual copper production in 2016 was 4 percent up from a year ago, reaching 523,000 tons, however this figure was short of their expected range of 535,000 to 565,000 tons.

In a statement issued on Tuesday, the company blamed slower production at their Kennecott mine in the United States, a 21 percent fall in the fourth quarter output at their Oyu Tolgoi mine in Mongolia, and supply issues at their Grasberg joint venture in Indonesia.

Rio Tinto's chief executive, Jean Sebastian Jacques, was still upbeat about his company's prospects.

"We have delivered a strong operational performance in 2016, underpinned by our drive for efficiency and maximizing cash flow," he said in a statement, adding that Rio Tinto will maintain a disciplined business approach in 2017.

But in a note, Royal Bank of Canada analyst Paul Massey suggested Rio Tinto may have issues to address as "copper performance was disappointing with complications across the suite of assets contributing to softer overall production."

"We highlight the guidance range for FY17 is very large, suggesting further operational uncertainty remains," Massey said. Endit