By Barbara Lewis
LONDON (Reuters) - Anglo American (AAL.L) on Thursday reported a sharp production fall at its Los Bronces copper mine in Chile at the end of last year offsetting an overall increase in mineral output across its mines.
The dip in output late last year weighed on Anglo American shares, which fell around a percent by 1010 GMT, although analysts said Anglo American's figures were broadly positive.
They remain confident in the global mining sector, which recovered strongly last year led by Anglo American, the top performer in the FTSE 100 index (.FTSE) as the company's shares rebounded from a big sell-off in 2015.
Anglo American said it had seen operational improvements across its portfolio, but Los Bronces output was difficult, as grade quality deteriorated, weather was bad and contractors carried out "illegal industrial action," Anglo said.
"Together with positive contributions from ongoing ramp-ups at Minas-Rio, Grosvenor and Gahcho Kue, we will be reporting a 2 percent increase in copper equivalent production volumes for 2016 as a whole," CEO Mark Cutifani said in a statement.
For the final quarter of 2016, the Los Bronces problems led to a 19 percent fall in copper output compared with the same time a year ago.
Anglo American has put copper, along with platinum and diamonds, at the heart of its portfolio.
Production at its diamond business De Beers rose 10 percent in the last quarter of 2016 compared with a year earlier as output was boosted in line with improved trading conditions relative to a difficult 2015.
For platinum, up 2 percent, Anglo American said it continued to "maintain discipline by mining to demand".
Bernstein analysts said in a note the news was positive.
"Today's results do not materially change our view on the stock," it said, adding it maintained its "outperform" rating.
Also on Thursday, Kaz Minerals (KAZ.L), a copper company focused on large scale, low-cost open pit mining in Kazakhstan reported 73 percent year-on-year output growth as new production came online.
"We successfully ramped up Bozshakol and the Aktogay oxide plant," Chief Executive Oleg Novachuk said. "Our growth will continue in 2017 as Bozshakol reaches capacity and we commence production from sulfide ore at Aktogay."
Kaz Minerals also said full-year gross cash costs would be around 20 percent less than the previous guided range of 140 to 160 U.S. cents per pound of copper.
Share prices in the mining sector are broadly speaking extending last year's rally, but traders took profits in Kaz Minerals as well as Anglo American on Thursday.
Reversing earlier small gains, Kaz Minerals was also down around a percent, slightly more than a dip in the overall sector. <.FTNMX1770>
Copper prices on the London Metal Exchange (CMCU3) were roughly flat.
They jumped 18 percent last year, the first annual rise since 2012. Copper has been billed as the bulk commodity most likely to run into short supply, although output is still ample for now.
(editing by Susan Thomas and Jane Merriman)