The countries are monitoring a seven-day truce between the army and paramilitary Rapid Support Forces (RSF) that began on Monday, aimed at allowing access to aid and basic services.

Although fighting appears to have calmed, there has been no full pause in hostilities with reports throughout the week of clashes, artillery and air strikes.

"Although there was observed use of military aircraft and isolated gunfire in Khartoum, the situation improved from May 24 when the ceasefire monitoring mechanism detected significant breaches of the agreement," a Saudi-US statement said.

Saudi and US representatives "cautioned the parties against further violations and implored them to improve respect for the ceasefire on May 25, which they did", it said.

Some 1.3 million people have fled the fighting, which stems from a power struggle between the military rivals, seeking refuge within Sudan or neighbouring states.

The health ministry has said at least 730 people have been killed, although the true figure is likely much higher.

Those who remain in Khartoum suffer from electricity and water outages, a breakdown in health care services and reduced communications.

Many homes, particularly in well-off areas of the capital, have been raided and looted.

"When I heard it happened to us I wasn't that surprised," said Taysir Abdelrahim, who had left Sudan and found out her home was looted two days ago.

"Even if we were in Sudan there's nothing you can do about it.

"It's all part of the chaos of this war."

Food stores, flour mills and other essential facilities have also been looted.

The US Agency for International Development (USAID) head Samantha Power said late on Thursday enough grain to feed two million people was being delivered to Sudan by ship.

However, it is unclear how that and other aid that agencies say is ready will reach Khartoum and other hard-hit areas without security guarantees and bureaucratic approvals.

The Saudi-US statement said some aid had been delivered to Khartoum on Friday, without giving details.

The Red Cross has said it managed to deliver supplies to seven hospitals.

Telecom engineers were able to begin network repairs in Khartoum and elsewhere on Thursday, the Saudi-US statement said.

Outside the region, fighting has flared in several major cities to the west in recent days, according to activists, most recently in El Fashir, the capital of North Darfur state.

Further west, the cities of Zalingei and El Geneina have experienced a total communications blackout amid militia attacks.

Residents of the city of Nyala, one of the country's largest in South Darfur, said on Friday calm had returned after days of fighting between the army and RSF.

Within Khartoum, the army relies on air power while the RSF has taken cover in the streets.

It is unclear whether each side has gained an edge in recent weeks.

Australian Associated Press