BHP has signalled the cost of remediation at its oil and gas fields is $US3.9 billion, easing worries among investors at Woodside Petroleum about the liabilities to be assumed in the proposed $41 billion merger with BHP Petroleum.

The figure in BHP’s annual report released on Tuesday is the first breakout of petroleum clean-up provisions among the mining giant’s total provisions for closure and rehabilitation, which rose to $US11.9 billion ($16.2 billion) at the end of fiscal 2021, from $US8.8 billion 12 months earlier.