* First quarter output up year-on-year, down on Q4
* Maintenance at Los Pelambres erodes output increase (Adds comment, copper, share price movement)
LONDON, April 27 (Reuters) - Chilean miner Antofagasta is seeing signs of a more stable copper market, but said its focus was on cost after a fourth-quarter dip in output eroded some of the efficiency gains made over the year.
Antofagasta shares fell around 1 percent in opening trade in London and were 0.6 percent lower at 0744 GMT, while the UK mining index eased 1.2 percent..
"Movements in the copper price over the quarter may suggest the market is beginning to stabilise," Antofagasta CEO Ivan Arriagada said in a statement on Wednesday.
"However, with price growth likely to remain subdued in the near term, our focus continues to be on operating safely, efficiently and profitably."
First-quarter output of 157,100 tonnes was up 7.3 percent from a year earlier but down 7.5 percent versus the final quarter of 2015.
The company's joint venture at Zaldivar in northern Chile and extra production at Antucoya added 25,000 tonnes of production, but output declined versus the fourth quarter because of maintenance at Los Pelambres.
Net cash costs declined by 4.2 percent compared with the first quarter of 2015 as higher revenue from gold sales offset the impact of lower copper production in the final quarter of last year.
Bernstein said in a note the results "exhibited positives in terms of costs".
Antofagasta and other miners have been hit by a slide in prices and slower growth in China. Benchmark copper futures fell by 19 percent last year, touching 6-1/2-year lows in January.
On Wednesday copper futures eased 0.9 percent. (Reporting by Barbara Lewis; editing by Jason Neely and Louise Heavens)