Mota-Engil is set to sign a 30-year concession with the Democratic Republic of Congo to operate a key copper and cobalt railway, potentially backed with up to $1-billion of US financing.

The deal with Portugal’s biggest construction company covers the rehabilitation and management of the Congolese portion of the Lobito Corridor, an infrastructure project that aims to increase exports of critical minerals to Western markets, according to people familiar with the matter. Mota-Engil is already part of the consortium operating a connecting rail line in neighbouring Angola that runs to a port on the Atlantic Ocean coast.

Congo’s government and Mota-Engil are due to sign an agreement on Wednesday in the African nation’s capital, Kinshasa, the people said, asking not to be identified discussing matters that aren’t yet public. The contract will run for three decades, some of the people said.

A representative for Mota-Engil declined to comment. A spokesperson for Congo’s presidency didn’t immediately respond to a request for comment.

Minutes of a Congolese ministerial meeting held last month revealed that the parties were working on a public-private partnership intended to revive the dilapidated 1,000-kilometer (620-mile) railway, which passes through the mining hubs of Kolwezi, Tenke and Lubumbashi, Bloomberg News previously reported.

The Angolan section of the Lobito Corridor, which Mota-Engil manages in a joint venture with Trafigura Group, has received financial backing from the US International Development Finance Corp (DFC). President Donald Trump’s administration has also been supportive of the Portuguese firm’s efforts to win the deal in Congo.

In December, the DFC said it had signed a letter of interest with Mota-Engil for financing of as much as $1-billion to help the firm repair and operate the rail line in Congo.

Congo is the world’s second-biggest copper producer and top source of battery metal cobalt. US interest in the country’s natural resources has intensified since Trump returned to the White House as he seeks to reduce dependence on Beijing for a wide range of mineral products.

While the US and Congo concluded a partnership in December granting American investors preferential access to some metal deposits, Chinese miners like CMOC Group and Zijin Mining Group currently account for most of the African nation’s copper and cobalt output.

There’s also a separate project to connect Zambia – Africa’s No. 2 copper producer – to the Lobito Corridor. At the same time, Chinese firms are progressing with a $1.4-billion overhaul of an export railway that can move minerals from Zambia to the Indian Ocean port of Dar es Salaam in Tanzania.

The Mota family is Mota-Engil’s largest single shareholder and holds the top executive posts at the firm, while China Communications Construction Co owns a 31% stake. The company has engineering, industrial and mining projects across Africa and South America, as well as in Spain and Portugal.