Katrina Manson/Reuters

LONDON – The mining company First Quantum Minerals has begun an improved takeover offer of 5.1 billion Canadian dollars, or $5.2 billion, for a rival, Inmet Mining, in its latest effort to buy the copper producer.

First Quantum, which operates mines from Australia to Zambia, said late on Sunday that it had offered Inmet Mining’s shareholders a cash-and-stock deal valued at a $72.87 for each share in the Canadian miner.

The renewed bid for Inmet Mining represents a slight increase from a previously rejected $70.85-a-share takeover approach for the copper producer, and a 36 percent premium on the mining company’s closing share price before it rejected First Quantun’s initial advances.

Inmet Mining’s board had rebuffed an earlier offer in late November valued at $63.26 a share.

The proposed deal follows the announcement of the $32 billion takeover by the commodities trader Glencore for the mining giant Xstrata. Despite concerns that a downturn in Asian economies could hurt short-term demand, companies are seeking to gain access to metals and minerals in expectation that fast-growing economies will soon rebound.

First Quantum, which is based in Vancouver, British Columbia, said the proposed deal would create one of the world’s leading copper producers that could produce around 1.3 million metric tons of the metal each year by 2018.

The mining company said it had taken its takeover approach directly to Inmet Mining’s shareholders, and called on the company’s board to reconsider its multibillion-dollar offer. First Quantum added that it had held discussions with a number of Inmet Mining’s top investors about the proposed deal. The company did not say which investors it had contacted.

“We believe strongly in the prospects of a combination for our two companies,” First Quantum’s chief executive, Philip Pascall, said in a statement. “Our clear preference remains to engage with Inmet, as we believe strongly in the compelling strategic and financial merit of the transaction.”

Inmet Mining said on Monday that it had not yet received First Quantam’s offer, and advised shareholders not to take any action until the company had evaluated the new approach.

The board “will recommend a course of action that is in the best interests of Inmet and its stakeholders,” the company said in a brief statement.

Inmet Mining, which is based in Toronto, owns the Cobre Panama copper project, one of the world’s largest remaining untapped deposits of the metal. The mining company said it expected to spend more than $6 billion to develop the site, and recently announced a 27 percent increase in the project’s copper deposits.

First Quantum said that it would finance the takeover through its cash reserves and $2.5 billion of bank credit.

Jefferies International, Goldman Sachs and RBC Capital Markets are advising First Quantum on the deal.