The UN’s Deputy Spokesperson said Secretary-General António Guterres was “deeply alarmed” by the surge in attacks across South Kivu, where what’s officially known as the Alliance Fleuve Congo/Mouvement du 23 mars (AFC/M23) has advanced into several towns since 2 December.

The UN and Security Council have repeatedly described the majority-Tutsi M23 militia as backed by Rwanda but Kigali has consistently denied providing support.

“The Secretary-General underscores that this escalation risks seriously undermining efforts to achieve a sustainable resolution of the crisis and increases the risk of a broader regional conflagration,” Farhan Haq said in a statement.

Dozens of civilian deaths and many more injuries have also been reported in Kamanyola, Luvungi, Katogota and Uvira triggered mass displacement and caused civilian casualties.

Mr. Guterres called for an “immediate and unconditional cessation of hostilities,” urging all parties to honour commitments made under the peace accords signed by the leaders of DRC and Rwanda in Washington on 4 December and the Doha Framework Agreement reached in November.

He added the UN remains “fully mobilised” to support lifesaving assistance and ongoing diplomacy, stressing that “the risk of regional conflagration is real, and the need for de-escalation is urgent.”

Dramatic escalation

The UN aid coordination office (OCHA) said new assessments indicate that more than 500,000 people have been displaced in just over a week, a dramatic rise from earlier estimates.

While some families have returned to areas where fighting has momentarily subsided, most remain in overcrowded sites where the risk of cholera, mpox and other disease outbreaks is rapidly rising.

In the key town of Uvira – reportedly overrun by AFC/M23 fighters on Wednesday – the situation was described as relatively calm on Thursday, though sporadic gunfire continued in several neighbourhoods.

Radio Okapi, operated by the UN peacekeeping mission MONUSCO, reported that the city’s streets were deserted, the border crossing with Burundi closed, and residents sheltering indoors amid fear and uncertainty.

Hospitals ‘struggling to cope’

Hospitals are struggling to cope. Uvira’s main referral hospital is receiving a steady influx of wounded patients, including more than 60 people transferred after Ruzizi Hospital ceased operations due to insecurity.

On Wednesday, an explosion in Uvira’s Kimanga neighbourhood reportedly killed two civilians and injured three others.

More than 27,000 people have fled into Tanganyika Province, which borders South Kivu, since 8 December, arriving in Kisongo, Kabimba and along the shores of Lake Tanganyika.

Regional spillover fears

The violence has also driven people across DRC’s borders – an estimated 50,000 people have crossed into Burundi, where conditions at makeshift sites remain “very precarious,” according to OCHA.

Many refugees – mostly women and children – are exhausted, injured and in urgent need of shelter, food, water, sanitation and protection services.

Additional arrivals have also been reported in Rwanda, where the UN refugee agency, UNHCR, is supporting registration, health and nutrition services, hot meals and child protection assistance at the Nyarushishi Transit Centre.

A year of escalating conflict

The latest surge comes after one of the most volatile years in eastern DRC in recent memory.

Fighting between the Congolese armed forces, local militias and M23-aligned fighters intensified sharply earlier this year, culminating in the fall of Goma in January and repeated waves of displacement across North and South Kivu.

UN Special Envoy for the Great Lakes Region Huang Xia said the newest escalation “seriously undermines prospects for a durable settlement” and risks igniting broader regional tensions.

He urged all armed actors to step back from confrontation and facilitate rapid, unhindered humanitarian access.