Twice rejected, Nova raised its offer to $5.5 billion for the acquisition of copper company KAZ.

Nova Resources, the bidding consortium of copper miner KAZ Minerals, raised its offer by 9 per cent to £4.02 billion (about $5.5 billion) after it was rejected by minority shareholders because it had been too low.

Nova, which is controlled by KAZ chairman Oleg Novachuk and billionaire Vladimir Kim, said it would pay 850p a share, plus a special dividend, which would raise the total offer to 869p per share, with a majority stake in KAZ Minerals, with a 61 per cent share.

The final offer is higher than the 780p a share in February and the 640p a share first proposed last October. But previous offers were rejected by minority shareholders on the grounds that they were too low.

Commenting on the increased offer, Novachuk said Nova had listened to shareholders who were not satisfied with the previous offer.

Novachuk added: "the dynamics of the copper market have changed since the original offer was announced in October 2020, and the increase in the final offer fully reflects this change."

Metal prices have soared over the past six months, rising to a 10-year high of nearly $9500 a tonne before falling back to about $8680 on Thursday.

Copper is in high demand for renewable energy and electric vehicles, but new deposits are rare and increasingly difficult to recycle.

KAZ Minerals, a London-listed company, bought the Baimskaya copper mine in eastern Russia in 2018.

Although the mine is considered one of the most important underdeveloped copper mines in the world, its share price fell after the acquisition was announced, mainly hit by investor concerns about Russian political risks.

The cost of developing the mine is estimated to be close to $8 billion, and Nova noted on Friday that the risks to the project include a potential surge in costs, increased working capital requirements and liabilities related to long-term logistics contracts.

Under UK takeover rules, accepting the offer would mean that the company would be privatised after 16 years of listing on the London stock market. The deadline for Kaz to accept the offer is April 9.