Anglo American posted an annual loss of $3.1 billion on Thursday after taking an impairment of $3.8 billion, mostly due to its ailing diamond unit, as it races to restructure into a major copper producer following a bruising takeover battle with BHP last year.

The miner wrote down the value of its embattled diamond business again as it seeks to ready the division for disposal.

Anglo is considering either selling or listing De Beers, the carrying value of which is now about $4bn. That includes about $2bn worth of stock, a similar amount to last year.