Three American citizens jailed over a failed coup attempt in Democratic Republic of Congo were handed over to US custody on Tuesday, officials said, following high-level talks between the two countries on security and mining deals, the Congolese presidency told Reuters on Tuesday.

The presidency said the Americans had been transferred to US authorities after their sentences were commuted last week to serve their time at home.

The deal to hand over the Americans was finalised when US President Donald Trump's senior Africa adviser, Massad Boulos, traveled to Congo to hold meetings with President Felix Tshisekedi in the capital Kinshasa.

Their release comes at a time of intensifying negotiations between Washington and Kinshasa. The United States is open to exploring critical minerals partnerships, the State Department told Reuters last month, after Congo pitched a minerals-for-security deal to the Trump administration.

Ahead of the trip, Trump's special envoy for hostage response had called on Tshisekedi to release the Americans.

"This shows that the collaboration and cooperation between the two states is growing stronger and stronger," said Tina Salama, Tshisekedi's spokesperson.

The White House did not respond to a request for comment. The State Department said in an email that bringing home Americans was a top priority for the administration.

Joseph Szlavik-Soto, a lobbyist working for Kinshasa, said the Congolese had also agreed to pay for the damage caused by protesters who attacked the US embassy and other missions earlier this year.

The State Department declined to comment on the matter.

Congo wants the US to play a bigger role in securing the war-ravaged country, where fighting in the east has raised fears of a wider regional conflict.

The violence has escalated since January, when Rwandan-backed M23 rebels made a swift advance, capturing the two largest cities in the east.

Washington is interested in securing greater access to Congo's minerals, which are used in mobile phones and electric cars, and are currently exploited predominantly by China and its mining companies.

The Trump administration hasn't said how it might provide security, but a former senior defense official said options could include providing troops or contractors to train Congolese forces.

"I hope it could work in a fashion that respects human rights and contributes to long-term stability in this important region. This will be very challenging in the DRC context," the official said.

The Americans were among 37 defendants in Congo sentenced to death by a military court in September.

The coup attempt last May was led by Christian Malanga, a US-based Congolese politician, whose 22-year-old son was among the Americans arrested.

Marcel Malanga, who was visiting Congo with a high school friend, said at the trial his father had threatened to kill them if they did not obey his orders. His mother posted a statement on Facebook saying the family needed time and did not wish to comment.