A power struggle between Sudan's army and a notorious paramilitary force has rocked the country, with more than 50 civilians reported dead.

Residents dodged gunfire in the capital, Khartoum, as rival forces battled over the presidential palace, state TV, and army headquarters.

Twenty-five people, including 17 civilians, have died in the city, a doctors' organisation said.

The clashes erupted after tensions over a proposed transition to civilian rule.

Both the army and its opponents, the Rapid Support Forces (RSF), claimed they had control of the airport and other key sites in Khartoum, where fighting continued overnight.

Heavy artillery was heard in Omdurman, which adjoins Khartoum, and nearby Bahri in the early hours of Sunday morning. Eyewitnesses also reported gunfire in the Red Sea city of Port Sudan.

The army said jets were hitting RSF bases, and the country's air force told people to remain in their homes on Saturday night while it conducted a full aerial survey of paramilitary activity.

Residents of Khartoum told the BBC of their panic and fear, with one describing bullets being fired at the house next door.

At least 56 civilians have been killed in cities and regions around the country, a Sudanese doctors' committee said, adding that dozens of military personnel were dead, some of whom had been treated in hospitals.

In total, at least 595 people had been injured, it said.

Three employees for the World Food Programme (WFP), a UN body that delivers food assistance to vulnerable communities, were killed after the RSF and armed forces exchanged fire at a military base in Kabkabiya, in the west of the country.

Generals have been running Sudan since a coup in October 2021.

The fighting is between army units loyal to the de facto leader, Gen Abdel Fattah al-Burhan, and the RSF, commanded by Sudan's deputy leader, Mohamed Hamdan Dagalo, also known as Hemedti.

Hemedti said his troops would keep fighting until all army bases were captured.

In response, Sudan's armed forces ruled out negotiations "until the dissolution of the paramilitary RSF".

In Khartoum, people were filmed running away and taking cover as black smoke rose over the city.

A Reuters journalist said there were armoured vehicles in the streets, while video showed a civilian plane ablaze at Khartoum airport. Saudi airline Saudia said one of its Airbuses came under fire.

Numerous airlines have suspended flights to Khartoum and neighbouring Chad has closed its border with Sudan.

"We don't have any electricity," a British-Sudanese doctor, who is visiting relatives in Khartoum, told the BBC. "It is hot. We can't afford to open the windows, the noise is deafening."

Another eyewitness speaking to the BBC via her Kenya-based sister said: "Shooting is still ongoing and people are staying indoors - there is so much panic and fear."

Residents had not been expecting the clashes, she said, and many had been caught in transit, with bridges and roads closed and many schools in lockdown.

Duaa Tariq was speaking to the BBC when a military plane flew over her building. "They're shooting live ammunition at the roof of the house next door and we're just now taking shelter," she said.