• Anglo American rejected a third takeover proposal from rival BHP Group on Wednesday, as the companies agreed to extend talks deadline by one week.
• The British miner confirmed the third proposal from BHP offered about £29.34 per Anglo American share.
• The bid also once again included demands for Anglo to unbundle its platinum and iron ore assets in South Africa, a process Anglo has previously deemed too risky and complex.

LONDON — Anglo American rejected a third takeover proposal from rival BHP Group on Wednesday, as the companies agreed to extend the talks deadline by one week.

The British miner confirmed the third proposal from BHP offered about £29.34 ($37.33) per Anglo American share, based on undisturbed share prices as of the market close on April 23. The offer values the company at £38.6 billion, according to Reuters.

The bid also once again included demands for Anglo to unbundle its platinum and iron ore assets in South Africa, a process Anglo has previously deemed too risky and complex.

"The Board considered BHP's Latest Proposal carefully, concluded it does not meet expectations of value delivered to Anglo American's shareholders, and has unanimously rejected it," Anglo American Chairman Stuart Chambers said in a statement on the London Stock Exchange website.

"However, the Board is willing to continue to engage with BHP and its advisers on this topic and has therefore requested a one week extension to the PUSU deadline which has been consented to by the Panel," Chambers added.

Before discussions were extended, under U.K. takeover rules BHP previously had until 5:00 p.m. London time to make a formal and final offer for Anglo following a drawn-out four-week bidding battle.

Shares of Anglo American rose shortly after the announcement before paring gains to trade down 0.6% by 4:10 p.m. London time. BHP shares fell more than 3.7%.

The Australia-based mining and metals giant made two prior nonbinding offers for Anglo as it seeks to shore up its dominance in the copper industry given the metal's key role in the energy transition and products such as electric vehicles, power grids and wind turbines.

The combined companies would form a behemoth in copper mining and the world's largest player in the space, supplying 10% of global output, according to a Reuters analysis.

Anglo rejected both previous offers, however, saying they "significantly undervalue the company and its future prospects."

BHP's earlier offers included requirements for Anglo to de-merge from Anglo American Platinum Ltd. and Kumba Iron Ore Ltd., two entities which together account for a sizeable proportion of the company's copper production. Chambers said at the time that the proposal created "substantial uncertainty" and executive risk for the company.

Anglo later announced plans to spin off its highly prized De Beers diamond unit, as well as its steelmaking coal, nickel and platinum businesses, as part of a sweeping restructuring of its 107-year-old business.

Anglo CEO Duncan Wanblad said the restructuring was part of existing efforts to "streamline the business and provide greater value to shareholders."

The takeover offensive paves the way for a return of mega-deals after more than a decade of quiet in the mining industry. Copper's recent rally has also heightened demand in the space, with BHP rival Rio Tinto similarly expanding its business in the base metal.