Sudan's army appeared to gain the upper hand on Sunday in a bloody power struggle with rival paramilitary forces, pounding their bases with air strikes, said witnesses.

At least 97 civilians had been killed and 365 injured since the fighting in started, said one doctor's group.

The fighting erupted on Saturday between army units loyal to General Abdel Fattah al-Burhan, head of Sudan's transitional governing Sovereign Council, and the paramilitary Rapid Support Forces (RSF), led by General Mohamed Hamdan Dagalo, known as Hemedti, who is deputy head of the council.

It's the first such outbreak since both joined forces to oust longtime ruler Omar Hassan al-Bashir in 2019 and was sparked by a disagreement over the integration of the RSF into the military as part of a transition towards civilian rule.

Burhan and Hemedti agreed to a three-hour pause in fighting from 4 p.m. local time to allow humanitarian evacuations proposed by the United Nations, the U.N. mission in Sudan said, but the deal was widely ignored after a brief period of relative calm.

As night fell residents reported the boom of artillery and roar of warplanes in the Kafouri district of Bahri, which has an RSF base, across the Nile river from the capital Khartoum.

Eyewitnesses told Reuters the army was renewing air strikes on RSF bases in Omdurman, Khartoum's sister city across the Nile, and the Kafouri and Sharg El-Nil districts of adjacent Bahri, putting RSF fighters to flight.

The United States, China, Russia, Egypt, Saudi Arabia, the U.N. Security Council, European Union and African Union have appealed for a quick end to the hostilities that threaten to worsen instability in an already volatile wider region.

Efforts by neighbors and regional bodies to end the violence intensified on Sunday. Egypt offered to mediate, and regional African bloc Intergovernmental Authority on Development plans to send the presidents of Kenya, South Sudan and Djibouti as soon as possible to reconcile Sudanese groups in conflict, Kenyan President William Ruto's office said on Twitter.

The eruption of fighting over the weekend followed rising tensions over the RSF's integration into the military. Discord over the timetable for that has delayed the signing of an internationally-backed agreement with political parties on a transition to democracy after a 2021 military takeover.

(Cover: Smoke rises as clashes continue in the Sudanese capital on April 17, 2023 between the Sudanese Armed Forces and the paramilitary Rapid Support Forces (RSF). /CFP)