The United Nations refugee agency confirmed Tuesday that the number of people who have fled the fighting in Sudan was now more than 500,000 while 2 million are internally displaced.

"Today we pass the mark of half a million refugees from Sudan following the beginning of the conflict," the head of the UNHCR Filippo Grandi said at a press conference in Nairobi.

"Two million people are displaced inside the country."

Sudan has been riven by conflict since April 15, with the army led by Abdel Fattah al-Burhan battling the paramilitary Rapid Support Forces (RSF) commanded by his former deputy, Mohamed Hamdan Daglo.

"If we don't silence those guns, the exodus of Sudanese people will continue," said Grandi, the United Nations High Commissioner for Refugees.

He was speaking on World Refugee Day, a day after donors at a U.N. conference pledged close to $1.5 billion to combat the humanitarian crisis in Sudan and help its neighbors host those fleeing the fighting.

More than two months into the fighting, the United Nations voiced fears the crisis could spill over and destabilize neighboring African states.

Donors pledge $1.5 billion

U.N. Secretary-General Antonio said $3 billion was needed and warned that the country was descending "into death and destruction" at breakneck speed.

"The scale and speed of Sudan's descent into death and destruction is unprecedented," he said. "Without strong international support, Sudan could quickly become a locus of lawlessness, radiating insecurity across the region."

Guterres said that hundreds of civilians had been killed and many thousands more injured since clashes erupted in mid-April.

"These numbers grow by the day. The situation in Darfur and Khartoum is catastrophic. Fighting is raging with people attacked in their homes and on the street," Guterres said.

"Before this conflict erupted, Sudan was already grappling with a humanitarian crisis. This has now escalated into a catastrophe affecting more than half the country's people."

He condemned violence against aid workers and the looting of humanitarian supplies and appealed to the warning parties to protect civilians and enable humanitarian action.

U.N. Human Rights chief Volker Türk reiterated his willingness to mediate between both parties to the conflict.

"I have also urged all States to help advance a resolution to this catastrophe. Yet efforts to pursue and sustain a ceasefire have produced little to no success," he said.

"We still see a reckless, senseless conflict taking place in a context of total impunity. The streets of Khartoum and its surrounding cities, of El Geneina and of El Obeid are stained with the blood of civilians."

The head of the U.N. refugee agency Filippo Grandi said the commitment showed by donors to those affected "comes just in time," as the agency's resources were dwindling.

"The pledges will save lives and help alleviate some hardship. Ultimately, of course, only a durable peace will allow the Sudanese to restart their lives," he added.