BP has agreed to buy US renewable gas producer Archaea for US$4.1 billion to help the British oil giant reach net zero carbon emissions by 2050, the two parties said on Monday.

The London-listed energy major is flush with cash after recent surges in oil prices that have triggered calls for the cash-strapped UK government to massively enlarge a windfall tax on British energy giants.

Chief executive Bernard Looney said in a statement Monday that the acquisition of Archaea would create "a real leader in the biogas sector, and support our net zero ambition".

Houston-based Archaea produces renewable natural gas equivalent in amount to about 6,000 barrels of oil per day.

BP will pay US$3.3 billion in cash plus around US$800 million in debt, while the purchase remains subject to regulatory and Archaea shareholder approvals.

The UK energy titan is attempting to pivot towards cleaner fuels to help tackle climate change.

In June, BP said it was taking a 40.5 percent stake in an Australian energy project being billed as one of the world's largest renewable power stations.

But energy majors are often faced with charges of corporate greenwashing, especially by environmentalists. Greenpeace has been calling on the British government to levy a substantial windfall tax on the sector.

Even the outgoing head of BP's rival Shell recently indicated that governments should "probably" tax energy firms more to help protect the poorest from rocketing energy bills. (AFP)