The miner posted an underlying net profit of $2.78 billion, compared with $4.08 billion a year earlier.

Scientists estimated the Hail Creek mine spewed between 123,000 and 263,000 metric tons of methane last year.

The world's no.1 miner had a busy six months marked by sweeping changes, including selling its $13 billion petroleum business and a listing unification, while managing pandemic-related disruptions to its business.

The agreement with the Yinhawangka Aboriginal Corporation will ensure that significant social and cultural heritage values are protected.

The top-five western diversified mining companies may see combined 2021 second-half earnings of $73 billion.