KHARTOUM: Clashes erupted on Tuesday between the Sudanese regular army and rival paramilitaries in Omdurman, Khartoum's twin city, with the army calling the fighting part of a "large-scale" offensive.

An AFP correspondent at the scene said explosions rang out in the area, where the paramilitary Rapid Support Forces (RSF) had retreated after losing control of the Sudanese capital in March.

The army said its operation which began on Monday was aimed at driving the paramilitaries from their last positions in Khartoum state.

"We are pressing a large-scale operation and we are close to clearing the whole of Khartoum state from dirty thugs," military spokesman Nabil Abdallah said in a statement.

The war since April 2023 has pitted the army headed by Sudan's de facto leader Abdel Fattah al-Burhan against the RSF under his former deputy Mohamed Hamdan Daglo.

The fighting comes as both the army and the RSF are attempting to establish their own governments.

On Monday, army chief Burhan has tapped a former United Nations official, Kamil Idris, as a new prime minister -- a move seen by analysts as an attempt to gain international recognition and present a functioning civilian-led government amid the ongoing war.

The African Union on Tuesday welcomed the appointment, calling it "a step toward inclusive governance" and expressing hope that the move will "restore constitutional order and democratic governance in Sudan".

The RSF announced in April it would form a rival administration, a few weeks after signing a charter in Kenya with a coalition of military and political allies.

In recent weeks, the RSF has staged multiple drone attacks on areas around the country, including Port Sudan on the Red Sea coast, the seat of the army-aligned government since the war began.

Omdurman, which is situated just across the River Nile from Khartoum, has been a focal point of fighting in recent days.

This week, a days-long electricity blackout hit the whole Khartoum state, following drone strikes blamed on the RSF on three power stations in Omdurman.

Medical charity Doctors without Borders (MSF) said on Sunday that the power outages had disrupted health services at the city's major hospitals.

"The magnitude of these drone attacks represents a major escalation in the conflict, with alarming implications for civilian protection," the UN's human rights expert on Sudan, Radhouane Nouicer, said in a statement on Monday.

"The recurrent attacks on critical infrastructure place civilian lives at risk, worsen the humanitarian crisis, and undermine basic human rights."

The army has meanwhile launched attacks in areas controlled by the RSF in the country's south, trying to claim territory and cut off rival supply lines.

The Emergency Lawyers, a monitoring group which has documented atrocities on both sides, on Sunday accused the army of killing 18 civilians, including four children, in an attack on Al-Hamadi village in South Kordofan state last week.

The war has killed tens of thousands, displaced 13 million and sparked what the United Nations describes as the world's worst humanitarian crisis.

The conflict has carved up Sudan, with the army controlling the north, east, and centre, while the RSF dominates nearly all of Darfur and parts of the south.