The head of Sudan's Rapid Support Forces (RSF) has claimed his fighters were prepared to wage war for decades against the country's regular army, warning that RSF forces remain positioned outside the army-controlled capital.

"We do not want this war to continue," RSF chief Mohamed Hamdan Daglo told a group of soldiers at an undisclosed location late Wednesday.

But "if they (the army) want it to go on for 40 years, it will continue until they are uprooted."

The remarks by Daglo came a day after Sudan's army-aligned government accused Ethiopia and the UAE of launching drone attacks since March on several states across Sudan from inside Ethiopian territory, including strikes on Monday against the capital Khartoum and its airport.

The UAE has been accused of arming the RSF but denies the allegation, while Ethiopia has denied hosting RSF and UAE forces on its territory.

Both countries also denied any involvement in the strikes, the details of which AFP could not independently verify.

Daglo said some RSF forces had not left the capital despite being largely ousted by the army last year and were still positioned on the outskirts of Omdurman, across the Nile River from central Khartoum.

Khartoum, which had seen relative calm since the army recaptured it, has been struck several times in the past couple of weeks.

On Saturday, a drone strike killed five civilians in a vehicle in southern Omdurman, while last week another attack damaged a hospital.

More than 1.8 million displaced people have returned to the city since its recapture, according to U.N. figures, only to find dilapidated infrastructure and limited access to electricity and water.

Drone attacks by both sides have escalated across Sudan in recent months, killing nearly 700 civilians since January, according to the U.N.

The war, now in its fourth year, has killed tens of thousands, displaced millions and created what the United Nations describes as the world's largest displacement and hunger crises.

Efforts to end the conflict – including those by the United States, Saudi Arabia, the United Arab Emirates and Egypt, a group known as the Quad – have so far faltered, with the two warring sides failing to agree on a humanitarian cease-fire.

Army chief Abdel Fattah al-Burhan has repeatedly said his forces will fight until victory, insisting the war will not end unless the RSF surrenders their weapons.

Outside the capital, fighting is raging on several other fronts, including in southern Kordofan and Blue Nile state near the Ethiopian border.