The Democratic Republic of Congo's mining unit wants to buy three of the Khazakh miner's assets in the country and has funds to finance the purchase, Robert Lukama, the chairman of Gecamines told Reuters.

Lukama declined to name the projects or mines Gecamines wants to buy but said the company is targeting three of ERG's several assets in the world's top cobalt supplier.

ERG didn't immediately respond to emailed questions.

"We have a firm proposal and we can confirm our proposal," Lukama said in an interview. "We showed our seriousness and we showed that we have the means to buy the assets."

Luxembourg-based ERG is 40% owned by the Kazakhstan government and its assets in Congo include Frontier mine, Comide, Metalkol, Boss Mining and some development and near-production assets.

Gecamines, which ranked among the world's top copper producers in the 1980s, is pushing for a bigger role in production and supply of critical minerals. Last year the state miner said it was leveraging its shareholding in joint ventures to secure rights to buy and trade in copper and cobalt.

Gecamines' offer is not conditional on the level of development or state assets are in and the miner is working hard to find common ground with ERG, Lukama said.

"We made an offer to buy some assets of ERG in good shape or not, it doesn't matter for us," he said. "We are still confident that we can convince them where the best interests are for us, for them and for the country."

He added that Gecamines is focused on creating value and is "entitled" to claim back undeveloped assets.

ERG has been negotiating with DRC authorities to lift the suspension of its Boss Mining operations. The government halted the operations in June last year after accusing ERG of polluting the environment.

Lukama said the loss of production at Boss Mining is depriving both shareholders of revenue. Gecamines owns a 49% stake in Boss Mining, which targets producing about 25,000 tons of copper and more than 3,000 tons of cobalt annually.