The UN Secretary General spoke of the “scale and speed” at which Sudan is descending into “death and destruction” at a high-level pledging event on Monday that drew donors from Saudi Arabia, Egypt, Qatar, the EU and the African Union.

Officials met in Geneva as Sudan enters its third month of conflict, although a second three-day Saudi-US-brokered truce between the warring Rapid Support Forces paramilitary group and the army was holding on Monday evening.

More than 2,000 people have been killed so far, the Armed Conflict Location and Event Data Project said, as a 72-hour truce brought rare calm to the capital, which has been the scene some of the worst fighting.

“The scale and speed of Sudan's descent into death and destruction is unprecedented,” UN Secretary General Antonio Guterres said at the opening of the conference.

He described the situation in Khartoum and Darfur as catastrophic.

Last week, the governor of West Darfur was killed hours after he said that a genocide was taking place there. The US blamed the RSF, primarily, for the mass killings of up to 1,100 people, including the governor.

Unverified videos showed the burning of entire villages.

“Fighting is raging with people attacked in their homes and on the streets,” Mr Guterres said, as the conflict affects more than half the country's people with 25 million now in need of aid.

“Deadly violence against aid workers and the looting of humanitarian property and supplies has made aid operations even more difficult and dangerous. Despite the challenges, UN agencies and partners have reached 1.8 million people in April and May,” he said.

The response plan for Sudan “does not meet the scale of the emergency”, Mr Guterres said, as only 17 per cent of the required nearly $3 billion needed for aid has been funded so far.

The latest figures from the World Food Programme show they have reached only 50,000 out of 500,000 beneficiaries in need of aid in Khartoum.

The WFP's representative for the Gulf Co-operation Council had previously told The National that the lack of access in Sudan was unprecedented.

"Without strong international support, Sudan could quickly become a locus of lawlessness, radiating insecurity across the region," Mr Guterres said.

Saudi Arabia has so far sent dozens of planes carrying assistance to Sudan. It was also one of the first countries to help in evacuating residents from numerous countries out of Sudan once the conflict began.

Saudi Foreign Minister Prince Faisal bin Farhan said the kingdom would “spare no effort to help people in Sudan” and has given $100 million through the King Salman Humanitarian Aid and Relief Centre, with “various assistance corridors by air and sea, in addition to a campaign that was launched since the beginning of the conflict”.

So far, Saudi Arabia has evacuated more than 845,000 people from more than 100 countries, he said.

Qatar's Prime Minister and Minister of Foreign Affairs Sheikh Mohammed bin Abdulrahman said the country backs Sudan's sovereignty and rejects any external intervention in the country's affairs.

Doha pledged $50 million in Monday's conference, Germany pledged $218 million in aid, the US pledged $171 million and the EU $210 million.

The EU's aid package includes almost $9 million for Sudan's neighbours that have taken in refugees, it said, without specifying which countries would receive it.

Egypt's Foreign Minister Sameh Shoukry also warned against the regional spillover from the conflict.

“Sudan's security and stability is our own,” he said. The Foreign Minister added that Egypt has so far welcomed more than 200,000 Sudanese citizens across its borders.

Earlier in the day, UN human rights chief Volker Turk told the Security Council that his office had received reports of at least 53 women and girls who had been raped in Sudan during the conflict.

He said about 20 of them were raped in a single attack.

“I am appalled by allegations of sexual violence, including rape,” Mr Turk said. He added that the RSF had been responsible in “almost all cases”.

He said he was allocating an additional $22 million to address Sudan's needs.

The International Committee of the Red Cross in Sudan warned on Monday of the collapse of the country's medical infrastructure.

“The onset of the rainy season has raised the fear of outbreaks of waterborne diseases,” the ICRC said in a statement.

“Garbage has not been collected in many urban neighbourhoods for weeks and dead bodies still lie in the open in some hard to reach areas.”

The National had earlier reported the rise of disease in Khartoum due to the lack of hygiene, including rotting corpses and waste left behind after massive looting operations.

Two out of three hospitals are not functioning in Khartoum, the UN said previously.