Sudan’s rival military forces have accused each other of fresh violations of a ceasefire that is set to expire as their deadly conflict continued for a third week despite warnings of a slide towards catastrophic civil war.

Hundreds of people have been killed and thousands wounded since a long-simmering power struggle between the Sudanese army and the paramilitary Rapid Support Forces erupted into conflict on April 15.

Locked in a battle for Khartoum, Sudan’s capital on the Nile, the parties have fought on despite a series of ceasefires secured by mediators including the US, the latest of which expires on Sunday.

The situation in Khartoum, where the army has been battling RSF forces entrenched in residential areas, was relatively calm on Sunday morning, a Reuters journalist said, after heavy clashes were heard on Saturday evening near the city centre.

The Sudanese army on Sunday said it had destroyed RSF convoys moving towards Khartoum from the west.

The RSF said the army had used artillery and warplanes to attack its positions in a number of areas in Khartoum province.

Reuters could not independently verify the reports.

In an apparent bid to boost its forces in the capital, the army said on Saturday that the Central Reserve Police had begun to deploy in southern Khartoum and would be deployed gradually in other areas of the capital.

The Central Reserve Police is a large and heavily-armed division of Sudan’s police force that has fighting experience from conflicts in the western region of Darfur and in the Nuba Mountains in southern Sudan.

In March 2022, the US imposed sanctions on the Central Reserve Police, accusing it of using excessive force against protesters who were demonstrating in Khartoum and other places against a 2021 military coup.

The fighting in Khartoum has meant RSF forces have fanned out across the city as the army tries to target them largely by using air strikes from drones and fighter jets.

This month’s conflict has sent tens of thousands of people fleeing into neighbouring states and prompted warnings that Sudan could disintegrate, destabilising a volatile region.

It has also derailed an internationally-backed political transition aimed at establishing democratic government in Sudan, where former autocratic President Omar Hassan al-Bashir was toppled in 2019 after three decades in power.

The prospects for negotiations have so far seemed bleak.

Army leader General Abdel Fattah al-Burhan has said he would never sit down with General Mohamed Hamdan Dagalo, also known as Hemedti. The RSF chief in turn said he would talk only after the army ceased hostilities.

Nonetheless, United Nations special representative in Sudan, Volker Perthes, told Reuters he had recently sensed a change in the sides’ attitudes and they were more open to negotiations, and were saying they would accept “some form of talks”.

At least 528 people have been killed and 4599 wounded, the health ministry said. The UN has reported a similar number of dead, but believes the real toll is much higher.

Foreign nationals have fled in one of the largest such evacuations since US-led forces withdrew from Afghanistan in 2021.

A US-government organised convoy arrived at the Red Sea city of Port Sudan on Saturday, evacuating US citizens, local staff and others.

The US government will help evacuees travel on to Jeddah, Saudi Arabia, US State Department spokesman Matthew Miller said. He did not say how many Americans remained in the country.

Britain’s foreign ministry on Saturday said it had evacuated 1888 people on 21 flights from since its evacuation operation started on Tuesday.