Anglo American Plc said it won’t give BHP Group any further time to commit to a takeover offer, threatening to end a US$49 billion pursuit by the world’s biggest mining company. 

The decision marks a dramatic climax to the five-week battle between two of mining’s biggest names, just hours before a 5 p.m. deadline for BHP to commit to an offer or walk away for six months. Anglo has repeatedly rebuffed proposals from BHP to partly break up and then acquire the 107-year-old company, but last week agreed to a one-week extension to a U.K. deadline in order to extend talks.

Anglo remains opposed to BHP’s complicated deal structure and the two sides have been unable to find a solution. BHP made a last-minute push to pressure Anglo’s board earlier on Wednesday, citing commitments it has made to help get the deal approved in South Africa and saying it believed the risks were manageable.

Just over three hours later, Anglo said its biggest concerns have still not been addressed. 

“BHP has not addressed the board’s fundamental concerns relating to the disproportionate execution risk associated with the proposed structure and the value that would ultimately be delivered to Anglo American’s shareholders,” it said. “The board has therefore unanimously concluded that there is no basis for a further extension.”

Anglo’s shares retreated as much as 7.6 per cent after its statement before paring some of the losses. 

Bloomberg has previously reported that BHP had no intention of going hostile with an offer directly to Anglo’s shareholders, which would also require it to buy the whole of Anglo, including the South African businesses. 

A successful takeover would have created a commodities powerhouse that towered over its closest rivals, significantly increasing BHP’s copper production at a time when miners and their investors are positioning for a prolonged period of tight metal supply and rising prices. The bid has also cemented the return to large-scale M&A among the largest mining companies, after a string of disastrous deals left BHP and its rivals on the sidelines for over a decade.

South Africa has loomed front and center of a potential deal ever since BHP’s approach first became public. It is home to some of Anglo’s biggest operations, employing tens of thousands of people, and the company has deep political and social ties to the country.

Anglo is concerned BHP’s demand that it first exit Anglo American Platinum Ltd. and Kumba Iron Ore Ltd. could leave the newly independent Johannesburg-listed companies to carry the cost of any concessions imposed by South Africa, reducing their value and ultimately penalizing the current Anglo investors who would receive the shares in the spinoffs. The multistep deal would require several layers of approval in South Africa, where deals are subjected to “public interest” assessment and authorities have a record of extracting substantial concessions from companies. 

As a result, Anglo, which this month rushed out a radical restructuring plan of its own, wanted BHP to either change the structure or commit to cover any future costs to its own shareholders.

BHP said in its statement earlier on Wednesday it was confident the deal would be approved and that the risks are “quantifiable and manageable,” based on similar transactions. 

BHP said it’s willing to discuss paying a break-up fee if the deal isn’t approved, without giving a proposed figure.

It has agreed to share in the costs of any additional employee-ownership requirements of the South African businesses and make commitments on issues like charitable spending and local procurement in South Africa. BHP noted that it had “already factored the costs associated with these risks into the offer ratio of its proposal.” 

Several of Anglo’s biggest shareholders said last week that they supported the company’s efforts to persuade BHP to change the structure of its takeover proposal or compensate for the risks it presented.