"Before the war, we were probably looking (at) around 38 percent of people living in poverty, and now we are estimating about 70 percent," said the UN Development Programme's Sudan representative Luca Renda, as the UNDP released a new report coinciding with the conflict's third anniversary.

The figures Renda cited were based on a poverty line of about $4 a day, and at least a quarter of the population is believed to be surviving on less than half that, he said.

Conditions are particularly severe in some of the worst-affected areas, including parts of southern Kordofan, now the main battleground, and North Darfur, where as many as 70 to 75 percent of people live in deprivation, Renda added.

Now entering its fourth year, the war between the army and the paramilitary Rapid Support Forces (RSF) has killed tens of thousands of people, displaced more than 11 million, and thrust several areas into hunger and famine.

Fighting has escalated in southern Kordofan and Blue Nile states, with surging drone attacks by both sides killing nearly 700 civilians since January, according to the UN.

In the capital Khartoum, however, a tentative calm has taken hold since the army regained control last year.

Reconstruction work has begun in parts of the city, with markets reopening and traffic picking up. Returns have been most visible in working-class districts that were previously largely deserted.

According to the UN, around 1.2 million people have returned to Khartoum since the army regained control.

Donors are due to gather in Berlin on Wednesday for an international conference on the conflict, aimed at reviving faltering peace talks and mobilising aid.

"We need action now -- to stop the violence, protect civilians, ensure access to communities in greatest danger, and fund the response," UN aid chief Tom Fletcher said on Tuesday.

- 'Systematic erosion' -

The humanitarian situation is dire.

"Three years into this conflict, we are not just facing a crisis -- we are witnessing the systematic erosion of a country's future," Renda said.

The UNDP report found that nearly seven million people were pushed into extreme poverty in 2023 alone, while average incomes have fallen to levels last seen in 1992.

Extreme poverty rates are now worse than in the 1980s, it said.

"These figures are not abstract," Renda said. "They reflect families torn apart, children out of school, livelihoods lost and a generation whose prospects are steadily diminishing."

More than 21 million people in Sudan face acute food insecurity, while two-thirds of the population urgently need assistance, according to the UN.

New research by the Norwegian Refugee Council found that only 15 percent of families say their living conditions allow them to live with dignity, while nearly one in three people receiving aid still share what little they have with others.

Save the Children said around 5.6 million babies were born during the war into conditions "no child should ever face", including overcrowded shelters, damaged health facilities or displacement.

"This conflict has really affected every single child in Sudan," Mohamed Abdiladif, the organisation's country director, told AFP, adding that more than 17 million children missed nearly two years of schooling, with eight million still not back in class.

The International Committee of the Red Cross said the number of missing persons has exceeded 11,000, up more than 40 percent in the past year alone.

Renda said recovery remains possible if peace is restored and reforms advance, but he warned that "every month of continued conflict makes it more difficult and more costly".

Peace efforts led by the United States, Saudi Arabia, the United Arab Emirates and Egypt have so far failed, and the Berlin conference is expected to make little progress in the absence of both warring sides.