The escalation in fighting comes amid deepening concerns about the vast humanitarian toll of the conflict.

Fighting has intensified across Sudan as the Rapid Support Forces (RSF) paramilitary group has launched attacks on the besieged city of el-Fasher in North Darfur and the North Kordofan city of Bara.

The RSF attacked Bara, a city 350km (215 miles) southwest of Khartoum, the capital, from multiple directions on Saturday morning, drawing artillery fire from the Sudanese armed forces (SAF), a military source told Al Jazeera.

The city is one of the largest urban areas under army control near the western front line with the RSF, but it is encircled by the paramilitary’s fighters.

Communications networks were cut off after the assault on North Kordofan’s second largest city. Clashes also continued in el-Fasher in the early hours with columns of smoke rising over the provincial capital as shelling and gunfire continued into the morning.

The paramilitary force published videos on Friday claiming its fighters had seized the North Darfur governor’s residence in el-Fasher and were now positioned near the SAF’s 6th Infantry Division headquarters, the army’s local command centre, according to the Sudan Tribune.

RSF fighters in the footage said they would advance on the city centre.

A source within the 6th Infantry Division was quoted by the Sudan Tribune as saying a “cautious calm” had settled over el-Fasher by Friday morning after what he described as a major attack the previous day.

However, residents trapped in the besieged city remained under fire. “It’s happening everywhere, even near me. An artillery shell landed about 100 metres [110 yards] away,” one el-Fasher resident told Al Jazeera.

The escalation comes as medical workers warned that the humanitarian situation has reached catastrophic levels. Dr Razan Al-Mahdi, spokesperson for the Sudan Doctors Network, said in a statement on Thursday that the crisis in el-Fasher had “surpassed all comprehension”.