A rebel leader in eastern Democratic Republic of Congo says his fighters will withdraw from a key city at the request of the US.

Corneille Nangaa's statement came days after US Secretary of State Marco Rubio said the capture of Uvira by rebel forces violated a peace deal, and the US would take action to ensure promises made to the President [Donald Trump] are kept.

Nangaa said that rebel forces would pull out of the city as a trust-building measure.

The US accuses Rwanda of backing the rebels. Rwanda denies the allegation, but its President, Paul Kagame, signed a peace accord on 4 December with his DR Congo counterpart, Felix Tshisekedi, at a ceremony in Washington hosted by Trump.

The US president hailed the deal as historic and a great day for Africa. The rebels were not signatories to it - and have been taking part in a parallel peace process led by Qatar, a US ally that has strong ties with Rwanda.

Nangaa is the coordinator of the Alliance Fleuve Congo (AFC), a coalition of rebel groups that includes M23, the most powerful force that European countries, along with the US, say is backed by Rwanda. DR Congo's army is supported by troops from neighboring Burundi.

The M23's capture of Uvira was a major blow to them, as the city is only 27km (17 miles) from Burundi's economic capital, Bujumbura, on the northern tip of Lake Tanganyika. Nangaa said, AFC/M23 will unilaterally withdraw its forces from the city of Uvira as requested by the United States mediation, adding that this was being done to give the Qatar-brokered peace process the maximum chance to succeed.

He did not indicate when the withdrawal would take place, but called for the deployment of a neutral force to monitor a ceasefire and to prevent DR Congo's army from regaining control of territory it had lost.

About 200,000 people have fled their homes in eastern DR Congo since the latest round of fighting started earlier this month, according to the UN. At least 74 people, mostly civilians, have been killed, and 83 others have been hospitalized with wounds.

The conflict has caused a humanitarian crisis in eastern DR Congo and neighboring states. Eastern DR Congo has been wracked by conflict for more than 30 years, with numerous peace initiatives aimed at ending the fighting having failed.

The Trump administration hopes that its peace initiative will pave the way for US companies to boost their investments in the resource-rich region, which includes an estimated $25 trillion in mineral reserves, including cobalt, copper, lithium, manganese, and tantalum - needed for electronic components used in various technologies.

The rebels began a major advance earlier this year with the capture of Goma, the capital of North Kivu province, and subsequently Bukavu, the capital of South Kivu province. The offensive on Uvira came just days before Kagame and Tshisekedi ratified the agreement in Washington.