BHP has moved on to focus on other growth opportunities after its failed bid for Anglo American earlier this year, the company's chairman said on Wednesday, weeks before a block on making another offer expires.

The world's biggest miner walked away from a $49-billion bid to acquire Anglo in May after it was rebuffed three times. The upcoming end in late November to a six-month freeze on BHP making another approach under UK takeover rules had raised speculation a deal may again be under scrutiny.

"We made an approach to Anglo American earlier this year ... we thought there was an opportunity here to create something unique and special, a bit of a sort of a one plus one equals three opportunity," BHP chairperson Ken MacKenzie said at the miner's annual meeting.

"Unfortunately, Anglo American shareholders had a different view, and they thought there was more value in the plan that their management wanted to execute. And so they moved on. And quite frankly, so have we."

As evidence, MacKenzie pointed to BHP's C$4.5-billion ($3.25-billion) deal with Canada-listed Lundin Mining in July to jointly take over developer Filo Corp  in a move to grow their copper holdings in South America.

At the meeting, a vote for BHP's climate action transition plan was supported by 91.77% of shareholders, despite some investors including Norway's sovereign wealth fund recommending a vote against the resolution due to a lack of details on the timing and scale of its emissions reduction plans.

BHP is slightly ahead of its target of reducing operational emissions by at least 30% by 2030 from 2020 levels, MacKenzie said. Its long-term goal is to achieve net zero operational emissions by 2050.

Among the four biggest iron ore miners, BHP has the least ambitious near-term target with the most aggressive, Fortescue aiming for zero operational emissions by 2030.

BHP was asked by one shareholder why it has applied to expand the life of its Queensland metallurgical coal mines that it jointly owns with Japan's Mitsubishi 8058.T by as many as 93 years if it is serious about mitigating climate change.

"I think the expansions you were referring to are actually a continuation of operations," CEO Mike Henry said.

"So even as we back efforts that would ultimately see the use of coal in steelmaking fall away, we recognise them for the foreseeable future," he said, adding that time period was likely to be decades, as forecast by BHP and others.

"Coal is likely to be required, and we believe we have a role to play in that," he added.