M23 militants have killed more than 100 people in a "generalized offensive" on Uvira, the Congolese government has said

Fighters from the M23 rebel group have seized a key city in the Democratic Republic of the Congo (DR Congo), intensifying their offensive in the mineral-rich east despite a high-profile US-brokered peace agreement signed last week.

The rebels entered Uvira shortly before midday on Wednesday and took control without a fight, according to local media. Uvira, located on Lake Tanganyika near the Burundi border, has been an important military and administrative base for Kinshasa in South Kivu following the capture of the provincial capital, Bukavu, earlier this year.

In a statement on Wednesday, the Congolese government said more than 100 people have been killed, over 200,000 newly displaced, and thousands more forced to flee in a "generalized offensive" on the Kamanyola-Uvira axis by Rwanda's Defense Forces and the rebels.

"Tactical weapons, notably suicide drones, have been used, causing human casualties among civilians and considerable material damage... and populations trapped by the attacks," it stated.

A spokesperson for the M23 said on social media that Uvira was "liberated" to protect civilians from "massacres committed by the coalition forces of the Kinshasa regime and their ally, Burundi."

The offensive comes less than a week after Congolese President Felix Tshisekedi and his Rwandan counterpart, Paul Kagame, signed a deal in Washington, which mediator US President Donald Trump hailed as a "historic" end to three decades of armed conflict in eastern DR Congo.

The accord commits Rwanda, which DR Congo has long accused of supporting the M23, to end its alleged involvement and withdraw its forces from the border. While previous ceasefire agreements have collapsed, Trump said Tshisekedi and Kagame assured him they will fully implement the latest agreement.

Kinshasa has called the situation in Uvira "a critical turning point" in the conflict, accusing Rwanda's leader of a "deliberate choice" to obstruct Trump's peace initiatives.

The Congolese government has called for punitive measures, including sanctions against Kigali, for its "blatant violations" and to pressure it into fully implementing the Washington accord.

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Kigali has rejected DR Congo's accusations, insisting that the escalation is the result of attacks by the Congolese army and its allies. Rwanda's Foreign Ministry said on Wednesday that Kinshasa has failed to observe the ceasefire and continues to pursue military solutions.