The London-listed miner, majority owned by Chile's Luksic family, said 2021 copper production fell 1.7% to 721,500 tonnes, which was within the range of the company's outlook.

For 2022 it forecast 660,000 to 690,000 tonnes, because of lower grades at some operations and an expected shortage of water.

Water is essential in copper production, used abundantly to separate the mineral from its ore and in subsequent steps.

To counter water shortages, many mining companies desalinate ocean water and use it in their processes.

Antofagasta is redesigning a desalination plant at its flagship Los Pelambres mine, for which costs are being reviewed. It expects to complete work on the concentrator plant expansion early in 2023.

For 2022, it expects capital expenditure of $1.7-1.9 billion, up from $1.6 billion in 2021, due to higher development costs at Los Pelambres.

Copper prices broke records in 2021 and Chile, which produces nearly 30% of the world's output, largely maintained production even during the worst of the pandemic. Copper is essential in construction and electric vehicle manufacturing.

(Reporting by Clara Denina in London and Priyanshi Mandhan in Bengaluru; editing by Jason Neely)