Rio Tinto Group and Saudi Arabia’s state-backed Manara Minerals Investment Co. are among suitors considering bids for a stake in First Quantum Minerals’ Zambian copper mines, according to people familiar with the matter.

Japanese trading houses Mitsui & Co. and Sumitomo Corp. have also been studying the assets, the people said, asking not to be identified as the talks are private. First Quantum is looking to sell a minority stake in its Sentinel and Kansanshi mines in Zambia and is seeking first-round bids in the coming weeks, they said.

The assets could also attract interest from Chinese companies such as Zijin Mining Group Co. and Jiangxi Copper Co., which is First Quantum’s second-biggest shareholder, the people said. The process is in the early stages and there’s no certainty the parties will proceed with bids.

Zambia accounted for about half of First Quantum’s copper output and revenue last year, and delivered more than $450-million in operating profit.

First Quantum is selling a stake in its Zambian assets after it was ordered to close its flagship copper mine in Panama last year following public protests. That left the company scrambling to refinance the debt it took on to build the mine. The firm sold about $1 billion in stock and raised $1.6 billion from a notes offering earlier this year and has said it may look at divesting smaller mining assets.

A spokesperson for Sumitomo said that the company continues to explore opportunities to acquire stakes in copper operations, declining to comment on specific deals. Spokespeople for First Quantum, Rio, Mitsui and Jiangxi Copper declined to comment. Representatives for Manara and Zijin Mining couldn’t immediately be reached.

The copper mines are attracting interest from a range of investors because demand for the metal is expected to soar in coming years. Copper is crucial for the production of electric vehicles and renewable energy infrastructure, while there is a lack of new mines being built.

And there are also relatively few good assets to buy. Some of the mines available in the central African copper belt, which stretches through Zambia and the Democratic Republic of Congo, aren’t appealing to buyers, and major firms are unwilling to sell stakes in their most important developments.

That means companies that have previously avoided taking stakes in mines in Africa — such as Japanese trading houses — have started to become more open to the possibility.

Rio, the world’s second-largest mining company, is generally reluctant to be a non-operator and has also avoided the central Africa region. The company’s copper head said at a recent conference that he sees much more value in building mines rather than buying existing assets. Still, the company has some ties with First Quantum and sold it a majority stake in a development project in Peru last year.

For Saudi Arabia, the deal would be another major coup following its purchase of a stake in Vale SA’s base metals unit for $2.6 billion. The kingdom is looking to secure supplies of metals for its industrial ambitions as it attempts to diversify its economy away from oil.