WASHINGTON

More than 180 people have been killed and 1,800 injured in armed clashes between military rivals in Sudan since the weekend, said the UN's envoy to Sudan on Monday.

"Fighting has been going on almost uninterruptedly. It's a very fluid situation. So it's very difficult to say where the balance is shifting to," Volker Perthes told reporters via teleconference.

The envoy's death toll figures come hours after UN Secretary-General Antonio Guterres appealed to Sudan's warring parties to immediately end the fighting, warning that continued hostilities risk the country's future as the death toll continues to mount.

Fighting erupted on Saturday between the Sudanese army and the paramilitary Rapid Support Forces in the capital Khartoum and its surroundings.

While the Rapid Support Forces accused the army of attacking its forces south of Khartoum, the military said the paramilitary force was "spreading lies" and declared it a "rebel" group.

Guterres strongly condemned the ongoing fighting, urging both sides to "immediately cease hostilities, restore calm, and begin a dialogue to resolve the crisis."