(Adds details on disruptions, costs)
By Silvia Antonioli
LONDON, April 29 (Reuters) - Chilean miner Antofagasta cut its annual copper production forecast on Wednesday as it posted a fall in first-quarter copper output hit by protests at one of its mines and heavy rains in the Atacama desert affecting some others.
Protests by a local community concerned about the shortage of water in the region blocked access to Antofagasta's Los Pelambres mine, denting production earlier this year, while unusually heavy rains in North Chile in March forced the company to suspend operations at Centinela, Michilla and Antucoya.
The London-listed miner, which like others in the sector faces falling ore grades and weak prices, produced 146,400 tonnes of copper in the quarter, down 13.6 percent from a year earlier and below analysts' forecasts.
It said production for the year will be around 15,000 tonnes lower that its previous forecast of 710,000 tonnes, but maintained its annual net cash cost forecast at around $1.40 per pound. Net cash costs in the first quarter, at $1.43 per pound, were roughly in line with analysts expectations.
The mining company, controlled by Chile's Luksic family, said construction of its Antucoya project was on track to be completed in the second quarter of this year and in full production by the start of next year.
Antofagasta is focusing on its $1.9 billion Antucoya greenfield project and other brownfield expansions to cope with a fall in production due to aging mines and declining copper grades. (Editing by Jason Neely, editing by Louise Heavens)