Tens of thousands of refugees escaping violence in Sudan are pouring into Chad, with aid agencies predicting an influx of even greater numbers.

Since fighting broke out in Sudan on April 15, an estimated 20,000 people have entered Chad, and at least 100,000 more are expected, the United Nations reported on Tuesday, raising concerns about the region's stability.

The conflict pits army chief Abdel Fattah al-Burhan against Mohamed Hamdan "Hemedti" Dagalo, the paramilitary Rapid Support Forces (RSF) leader and al-Burhan's lieutenant in the military's Sovereignty Council, which has ruled the country since the October 2021 coup. There have been over 400 deaths so far.

While the fighting has been most intense in the capital Khartoum, it has also spread to the western region of Darfur, reviving memories of the 16-year conflict in which 300,000 people were slain. During that time, rebels fought against the administration of President Omar al-Bashir and the Popular Defence Forces, which the rebels referred to as "Janjaweed" and which evolved into the RSF.

According to the United Nations, Chad, which shares a western frontier with Darfur, has reported the highest number of refugees from the Sudan conflict among its neighbors.

Idriss Mahmat Ali Abdallah Nassouri, the head of Chad's National Commission for Reception, Reintegration, and Returnees (CNARR), stated, "They arrive exhausted and in a state of panic after abandoning all their material and financial assets."

Most refugees have fled the towns of Nyala and El Geneina, the capital of West Darfur, where violence has been more intense, according to Nassouri, who added that the majority reside in Chad's Ouaddai and Sila provinces.

"The number of arrivals is increasing by the thousands, which is worrisome," Nassouri said, adding that resources were stretched to assist the 600,000 refugees who were already living in Chad before the latest crisis in Sudan erupted. These refugees are distributed across 13 camps in the country's east.

On Monday, the CNRR and the UN refugee agency (UNHCR) began pre-registering incoming civilians to Chad, identifying urgent needs and determining whether new sites were required or whether families could be relocated to existing reception centers.

In the meantime, the UNHCR has stated that it has dispatched water and sleeping mats to border villages.

Aid workers at the frontier reported receiving mostly women and children who had walked for more than two days with nothing but their clothes and food.

According to Alpha Koita, Chad's chief mission of Premiere Urgence Internationale, a French NGO operating in Chad, "the need is enormous." "They are mostly women and children who have abandoned everything," he said as his team deployed a mobile hospital in the Ouaddai hamlet of Adre.

Koita continued, "We need water, as access to it was difficult to even before the conflict; we need shelters, as people are sleeping under trees; and infrastructures for potable water and latrines to prevent diseases like cholera."

The monsoon season is expected to begin in June, further impeding humanitarian aid and forcing locals and refugees to compete for already scarce resources.

"If the conflict in Sudan continues, we will also see an increase in large-scale banditry and inter-ethnic conflict," Koita said.

Aid agencies were also concerned about their capacity to assist the new wave of refugees: "Services are already overstretched to support those who are already there, and the funding shortfall is critical to our ability to assist new refugees," said Eujin Byun, a spokesperson for the UN refugee agency. Since the beginning of the year, only 15% of the budget required to assist Chad's displaced population has been funded.

Due to Darfur's proximity, Chad has witnessed the most significant border crossing. However, aid workers have warned that civilians even further away will be affected.

"We must be vigilant in South Sudan, Ethiopia, and Egypt... People will move; it will take longer, but they will begin to arrive," said James Curtis, executive director of the Danish Refugee Council for East Africa. Curtis added, "This will only worsen as the crisis intensifies."

Sudan is home to 800,000 South Sudanese refugees, a quarter of whom reside in Khartoum, which is bombarded by gunfire and airstrikes.

Formerly a part of Sudan, South Sudan attained independence in 2011 following the conclusion of a decades-long civil conflict.

According to a UN memorandum, there has been a "daily increase" in arrivals. 4,000 South Sudanese have entered their native country, primarily through the Renk border crossing in Upper Nile State. Many South Sudanese are anticipated to arrive at the border crossing on foot. Most South Sudanese who have reached the frontier have done so via transportation.

Aid organizations were already concerned about the consequences of many people being forced to return to South Sudan, a country beset by a protracted ethnic conflict that has left nearly three-quarters of the population needing humanitarian assistance.

According to a UN report issued on Tuesday, the humanitarian repercussions of this crisis will be severe.