The nearly 90,000 refugees who fled to Burundi after the recent escalation of violence in eastern Democratic Republic of Congo face dire conditions in cramped camps with limited access to food and water, aid agencies say.

Congolese M23 rebels recently captured the city of Uvira, near the Burundi border, forcing hundreds of thousands from their homes. The rebels claim they have since withdrawn.

Medical charity MSF has been providing urgent assistance and raised concerns about the deteriorating humanitarian situation, especially for women and children who report going without food for days.

MSF has treated about 200 people daily since the influx of refugees began, with many in distress and exhaustion, including women giving birth while fleeing. The charity has warned of the risk of epidemic diseases, such as cholera and measles, among vulnerable populations.

The UN's World Food Programme announced it is ramping up life-saving aid to more than 210,000 affected individuals. However, services in South Kivu are reportedly collapsing, with health centers looted and schools closed.

The M23 rebels have gained significant territory in eastern DR Congo after also seizing major cities like Goma and Bukavu. Their reported withdrawal from Uvira comes amid claims from the Congolese government disputing the rebels' assertions.

Efforts for a peace agreement, mediated by the US, have been complicated by allegations of Rwandan support for the M23, although Rwanda denies this.