Rwanda-backed M23 rebels entered the eastern Congo city of Uvira, an important base for the country's military near the borders to Burundi and Rwanda, on Wednesday.

Lawrence Kanyuka, a spokesman for an alliance including M23 figthers, even claimed that its forces controlled the city, saying on social media that Uvira had been "liberated."

He alleged months of attacks on local citizens by Congolese and allied forces, saying this was the reason for the attack. He said displaced residents could now return, "freed from all harrassment and violence." 

The rebels' latest advance in the resource-rich South Kivu border region comes just days after Congolese President Felix Tshisekedi and Rwanda's Paul Kagame met with US President Donald Trump in Washington to declare their commitment to a US-brokered peace deal. 

Burundi closes border, says Rwanda giving 'middle finger' to US

Uvira is a city of more than half a million people that sits on Lake Tanganyika and the River Ruzizi, which form the natural borders between the DRC, Burundi and Rwanda. 

Burundi, which has thorny relations with Rwanda, announced on Tuesday afternoon that it had closed its border crossings with the DRC and now considered them "military zones." 

Foreign Minister Edouard Bizimana told Radio France Internationale on Wednesday that his country had registered more than 30,000 refugees from Congo in the past three days.

He also called for sanctions against Rwanda in an interview with the AFP news agency. 

"Signing an agreement and not implementing it is a humiliation for everyone, and first and foremost for President Trump," Bizimana said. "It's truly a slap in the face to the United States, a middle finger."

Uvira is only around 20 kilometers (roughly 12 miles) away from Burundi's economic capital and largest city, Bujumbura. The government in Gitega considers the city's fall to M23 fighters as an existential threat.

There were mixed reports on Wednesday on the status of fighting in the city, with some residents saying gunfire was still audible. But Reuters news agency cited a DRC military source as saying the army would not fight back to protect civilians, while AFP reported that some troops abandoned their weapons and uniforms and fled, looting as they left.

Uptick in fighting despite Trump's 'miracle' deal 

The US and nine other members of the International Contact Group for the Great Lakes issued a joint statement voicing "profound concern" at the renewed clashes in South Kivu. They called on M23 to "immediately halt" its advance and on Rwanda to withdraw its forces from DRC.

The M23's latest rapid advance began on December 1, parallel with Trump's efforts to advance a peace accord between the DRC and Rwanda in Washington. That agreement, hailed by the US president as a "miracle," featured efforts to secure US mining rights for valuable rare earth minerals like coltan. 

"They spent a lot of time killing each other," Trump said during the meeting. "And now they're going to spend a lot of time hugging, holding hands and taking advantage of the United States of America economically like every other country does."

The UN's OCHA humanitarian agency estimates that more than 200,000 people have been displaced from South Kivu province since December 2. Thousands more have crossed the nearby borders. 

Rwanda, accused of failing to withdraw its forces from the DRC border regions, in turn accused the DRC and Burundi of deliberately violating the terms of the peace deal in a statement issued on Wednesday. 

Edited by Sean Sinico