The sounds of air strikes, anti-aircraft weaponry and artillery could be heard in Khartoum and dark smoke has risen over parts of the city as fighting in Sudan enters a third week.

Fighting between the army and a rival paramilitary force continued despite the announcement of a 72-hour ceasefire extension on Friday when strikes by air, tanks and artillery rocked Khartoum and the adjacent cities of Bahri and Ombdurman.

Hundreds have been killed and tens of thousands have fled for their lives in a power struggle between the army and the paramilitary Rapid Support Forces (RSF) that erupted into violence on April 15, derailing an internationally-backed transition toward democratic elections.

The fighting has also reawakened a two-decade-old conflict in the western Darfur region where scores have died in the past week.

The army has been deploying jets or drones on RSF forces in neighbourhoods across the capital.

Trapped in their homes

Many residents are pinned down by urban warfare with scant food, fuel, water, and power.

At least 512 people have been killed and close to 4200 wounded, according to the United Nations, which believes the real toll is much higher.

More than 75,000 people were internally displaced within Sudan in the first week of the fighting, according to the UN.

Only 16 per cent of hospitals were operating as normal in the capital.

The latest ceasefire, brokered by foreign powers, is supposed to last until Sunday at midnight.

The RSF accused the army of violating it with air strikes on its bases in Omdurman, Khartoum’s sister city at the confluence of the Blue and White Nile rivers, and Mount Awliya.

The army blamed the RSF for violations.

The violence has sent tens of thousands of refugees across Sudan’s borders and threatens to stir instability across a volatile swathe of Africa between the Sahel and the Red Sea.

Foreign governments have evacuated diplomats and citizens to safety in the past week, including with airlifts.

Britain said its evacuations would end on Saturday as demand for spots on planes had declined.

The US said several hundred Americans had departed Sudan by land, sea or air.

Americans pull out

A convoy of buses carrying 300 Americans left Khartoum late on Friday on an 850km trip to the Red Sea in the first US-organised evacuation effort for citizens, the New York Times reported.

In Darfur, at least 96 people had died since Monday in inter-communal violence rekindled by the army-RSF conflict, UN human rights office spokeswoman Ravina Shamdasani said.

Releases and escapes from at least eight jails, including five in Khartoum and two in Darfur, were compounding chaos, she said.

In El Geneina, capital of West Darfur, a major hospital supported by medical charity MSF was looted, the group said.

“Many people are trapped in the midst of this deadly violence. They fear risking their safety and lives trying to reach the rare health facilities that are still functional and open,” said Sylvain Perron, MSF’s deputy operations manager for Sudan.

Relief agencies have been largely unable to distribute food to the needy in Africa’s third-largest country, where a third of its 46 million people were already reliant on donations.

Despite global appeals for talks, army chief General Abdel Fattah al-Burhan told US-based Arabic language broadcaster Al Hurra it was unacceptable to sit down with RSF head Mohamed Hamdan Dagalo whom he called “the leader of the rebellion”.

Dagalo, better known as Hemdeti, told the BBC that the RSF would not hold talks until fighting ends.

Saying the armed forces were “relentlessly” bombing his fighters, he blamed Burhan for the violence.

“Cease hostilities. After that we can have negotiations,” Dagalo said.

-AAP