LONDON, May 13 (Reuters) – BHP Group BHP.AX said on Monday that Anglo American AAL.L had rejected a revised buyout offer valuing the company at 34 billion pounds ($42.67 billion).

Anglo American had in April rebuffed BHP’s $39 billion all-share takeover proposal, saying it was opportunistic and significantly undervalued its prospects.

The new offer is 10% higher than BHP’s first one, or a 15% increase in the merger exchange ratio, lifting Anglo American shareholders’ aggregate ownership in the combined group to 16.6% from 14.8% in the earlier proposal, it said.

Anglo’s share price was down 0.7% at 27.58 pounds.

“We are disappointed that this second proposal has been rejected,” BHP’s CEO Mike Henry said in a statement.

“BHP continues to believe that a combination of the two businesses would deliver significant value for all shareholders,” the statement added.

The world’s biggest listed miner has until May 22 to log in a binding offer.

Anglo declined to comment.

Anglo is attractive to its competitors for its prized copper assets in Chile and Peru. The metal is used in everything from electric vehicles and power grids to construction, and demand for it is expected to rise as the world moves to cleaner energy and wider use of AI.

But the London-listed miner’s sprawling portfolio also includes platinum, iron ore, steelmaking coal, diamonds and a fertiliser project.

The revised bid is still contingent upon Anglo selling its shares in iron ore and platinum assets in South Africa, a country BHP exited in 2015.

Anglo’s investors are concerned that they stand to lose heavily by holding shares in the South African subsidiaries if they are unbundled.

($1 = 0.7968 pounds)

(Reporting by Clara Denina, Eva Mathews; Editing by Louise Heavens and Bernadette Baum)