Sudan's former Prime Minister Abdalla Hamdok has warned that the conflict in his country could become worse than those in Syria and Libya.

Speaking at a conference in the Kenyan capital Nairobi, he said the fighting between the regular army and the paramilitary Rapid Support Forces would be a "nightmare for the world" if it continued.

UN Secretary-General António Guterres also called on the parties to the conflict to de-escalate tensions and return to the negotiating table.

According to the Health Ministry, death toll from the ongoing clashes between rival forces has risen to 528 in Sudan. Early today, warplanes and heavy anti-aircraft fire were heard over the capital Khartoum, residents said.

Meanwhile, tens of thousands of people including foreigners have fled Sudan to neighbouring countries as the country entered a third week of fighting between Sudan army and Rapid Support Forces despite a ceasefire.

A ministry statement said that 4,599 people have also been injured in the violence during last fifteen days of clashes.