At least 185 people have been killed and a further 1,800 injured in three days of fighting between rival factions in Sudan, according to the United Nations special representative for Sudan, as the Group of Seven joined calls for an immediate to end to hostilities.

“It’s a very fluid situation so it’s very difficult to say where the balance is shifting to,” Volker Perthes said on Monday of the violence between the army and paramilitary forces led by rival generals.

According to international media reports, the two sides are using tanks, artillery and other heavy weapons in densely populated areas. Fighter jets thundered overhead and anti-aircraft fire lit up the skies as darkness fell.

Speaking to reporters in New York via video, Perthes also said that the warring sides were “not giving the impression that they want mediation for a peace between them right away”.

The sudden outbreak of violence over the weekend between the nation’s two top generals, each backed by tens of thousands of heavily armed fighters, trapped millions of people in their homes or wherever they could find shelter, with supplies running low in many areas.

As per reports, “gunfire and shelling are everywhere,” Awadeya Mahmoud Koko, head of a union for thousands of tea vendors and other food workers, said from her home in a southern district of Khartoum.

She said a shell stuck a neighbour’s house Sunday, killing at least three people. “We couldn’t take them to a hospital or bury them.”

The violence has raised the spectre of civil war just as Sudanese were trying to revive the drive for a democratic, civilian government after decades of military rule.

On Monday, UN Secretary-General Antonio Guterres again called on the warring parties to “immediately cease hostilities” warning that further escalation “could be devastating for the country and the region”.

In a joint statement on Tuesday, the G7 foreign ministers condemned the fighting.

“We urge the parties to end hostilities immediately without pre-conditions,” it said, calling for them to return to negotiations and reduce tensions.