Some 200,000 people have now fled Sudan to escape fighting that erupted in mid-April, in addition to hundreds of thousands who have been displaced inside the country, the UN said Friday.

"As violence in Sudan continues for a fourth week, nearly 200,000 refugees and returnees have been forced to flee the country, with more crossing borders daily seeking safety," UN refugee agency spokeswoman Olga Sarrado told reporters in Geneva.

The UN migration agency said earlier this week that more than 700,000 people have also been displaced within Sudan by the fighting that erupted on April 15, which has left more than 750 people dead and injured 5,000 others.

Speaking of the people fleeing the country, Sarrado warned that "the humanitarian response is challenging and costly," pointing out that "refugees and returnees are arriving in remote border areas where services and infrastructure are scarce or non-existent and the host population was already suffering due to climate change and food scarcity."

"The coming rainy season will make logistics even harder as many roads will become impassable," she said.

For neighbouring Chad, she said some 30,000 refugees had arrived in just recent days, bringing the total number who have arrived from Sudan in recent weeks to 60,000.

"Almost 90 percent of refugees are children and women, including many pregnant women," she said.

According to UNHCR, a full 20 percent of children between the ages of six months and five years had been found to be acutely malnourished.

Sarrado also meanwhile said UNHCR welcomed that Sudan's warring military factions signed a commitment to respect humanitarian principles in their spiralling conflict late Thursday.

The two sides promised in talks in the Saudi port city Jeddah late Thursday to protect civilians, but  nothing looked set to change immediately.

"We hope it will allow for much needed humanitarian assistance to be safely delivered and for essential services, like health care, water and electricity to be restored", she said.