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, and the fighting forced hundreds of thousands from their homes. The rebels say they have since withdrawn.

Medical charity MSF, which has been providing emergency help, has raised concerns about the worsening humanitarian situation.

The UN's refugee agency, UNCHR, indicated that those especially affected are children and women - including pregnant women - some of whom reported going without food for days.

MSF reported treating an average of 200 people daily since the refugees started arriving in Burundi two weeks ago. Zakari Moluh, MSF project coordinator, described the situation in Ndava, north-west Burundi, stating, We see people in a state of distress, despair, and exhaustion. We see women who gave birth while fleeing, some who give birth in our clinic.

The charity has warned about the risk of spreading epidemic diseases, including cholera and measles, as well as a catastrophic increase in malaria cases among vulnerable populations.

Meanwhile, the UN's World Food Programme (WFP) is ramping up its life-saving aid to more than 210,000 of the most vulnerable people displaced by the conflict. About half a million people have been forced from their homes in South Kivu province since the beginning of December.

The WFP is providing support to 71,000 new Congolese arrivals in Burundi with hot meals in transit centers.

The services in the province are on the brink of collapse. Health centers have been looted, medicines are unavailable, and schools remain closed. The agency has called for urgent funding to continue providing food aid in the next three months.

The recent capture of Uvira enhanced the M23's territorial gains in eastern DR Congo, after previously capturing major cities like Goma and Bukavu. Although the rebels announced their withdrawal from Uvira last week under pressure from the US, the claims have been disputed by Congolese authorities.

The US facilitated a peace deal between the Congolese and Rwandan governments to end the prolonged conflict, accusing Rwanda of backing the M23 rebels, which Rwanda denies. While the M23 was not party to the peace deal, they are involved in a separate peace process led by Qatar.