The company's De Beers business is now expected to produce between 32 million and 34 million carats compared with a previous target of 33 million to 35 million carats. Output in the fourth quarter slipped 14%. For 2020 production was down 18% year on year at 25.1 million carats.

The miner lowered its output in response to the COVID-19 pandemic, which disrupted the global supply chain and forced De Beers into restructuring its business.

"As we begin 2021 we are continuing to see positive demand for rough diamonds," Chief Executive Mark Cutifani said in a statement.

In commodities such as copper, platinum group metals and coal, the diversified miner kept all output targets unchanged. Anglo said it ran at 95% of 2019 rates in the second half of the year after COVID-19 disruptions in the first half.

Copper production climbed to 168,000 tonnes in the fourth quarter, up 6% from the previous quarter, while output of platinum group metals dropped by 7% and iron ore fell by 11%.

(Reporting by Zandi Shabalala; Editing by David Goodman)