Fierce clashes between Sudan's military and the country's powerful paramilitary force have erupted in the capital and elsewhere in the African nation, raising fears of a wider conflict in the chaos-stricken country.
Sudan has been marred in turmoil since October 2021, when a coup overthrew a Western-backed government, dashing Sudanese aspirations for democratic rule after three decades of autocracy and repression under Islamist ruler Omar al-Bashir.
Sudan's main pro-democracy coalition said loyalists of former strongman Mr Bashir, who was ousted in a coup in 2019, were fuelling a rift between the armed forces and a powerful paramilitary group that has jeopardised a transition to civilian government.
The paramilitary group, RSF, is under the rule of General Mohammed Hamdan Dagalo, known as Hemedti, who is deputy of the Sovereign Council.
The army is led by General Abdel Fattah al-Burhan, who is head of the Sovereign Council.
The army has rejected assertions by the RSF that they had seized the presidential palace, the army chief's residence and airports in Khartoum and the northern city of Merowe.
General Burhan told Al Jazeera TV: "We think if they are wise they will turn back their troops that came into Khartoum. But if it continues we will have to deploy troops into Khartoum from other areas."
Hemedti called General Burhan a "criminal" and a "liar".
"We know where you are hiding and we will get to you and hand you over to justice, or you die just like any other dog," he said in an interview with the station.
With conflicting versions of events given by the two sides, the situation on the ground was unclear.
The RSF, which analysts say is 100,000 strong, said the army had attacked it first, while the army said it was fighting the RSF at sites the paramilitaries said they had taken.
What is the RSF?
Created in 2013, the RSF emerged from the Janjaweed militia that then-president Omar al-Bashir unleashed against non-Arab ethnic minorities in the western Darfur region a decade earlier, drawing accusations of war crimes.
Over time, the forces grew, and were used as border guards in particular to clamp down on irregular migration.
In tandem, Hemedti's business interests grew with help from Mr Bashir, and his family expanded holdings in gold mining, livestock and infrastructure.
Beginning in 2015, the RSF, along with Sudan's army, began sending troops to fight in the war in Yemen alongside Saudi and Emirati troops, allowing Hemedti to forge ties with the Gulf powers.
In 2017, a law legitimising the RSF as an independent security force was passed.
Military sources said that the army's leadership had long expressed concern about the development of Hemedti's forces.
In April 2019, the RSF participated in a military coup that ousted Mr Bashir.
Later that year, Hemedti signed a power-sharing agreement that made him deputy of a ruling council headed by General Burhan.
A plan to integrate the RSF into the regular army is one of the key points of contention, analysts have said.
Eleventh-hour haggling between the two men over the details has twice forced postponement of the signing of an agreement with civilian factions setting out a road map for the transition.
So how did it get to this?
The clashes came as tensions between the military and the RSF have escalated in recent months, forcing a delay in the signing of an internationally backed deal with political parties to revive the country's democratic transition.
Tensions between the army and the paramilitary stem from a disagreement over how the RSF, headed by Hemedti, should be integrated into the military and what authority should oversee the process.
The merger is a key condition of Sudan's unsigned transition agreement.
Tension escalated on Thursday after it moved some of its forces near a military airport in the northern city of Merowe, which the army said happened without its consent.
On Friday, Hemedti said the RSF was committed to de-escalate and was ready to meet with General Burhan, in a statement by a group of officials including leaders of other paramilitary groups.
The RSF began redeploying units in the capital Khartoum and elsewhere amid talks last month, military sources told Reuters at the time.
Rivalry from Bashir era
The military rivalry dates back to the rule of autocratic former president Bashir.
Under Mr Bashir, the paramilitary force grew out of former militias known as Janjaweed that carried out a brutal crackdown in Sudan's Darfur region during the decades of conflict there.
Sudan began its halting transition towards democracy after military generals ousted Mr Bashir in April 2019.
Mr Bashir, an Islamist long shunned by the West, had presided over the country for nearly three decades.
Under an August 2019 agreement, the military agreed to share power with civilians ahead of elections.
That arrangement was abruptly halted by a 2021 coup, which triggered a new campaign of mass pro-democracy rallies across Sudan.
The military has been a dominant force in Sudan since independence in 1956, staging coups, fighting internal wars, and amassing economic holdings.
During the 2019-21 power-sharing arrangement, distrust between the military and civilian parties ran deep.
The civilian side drew legitimacy from a resilient protest movement and support from parts of the international community.
The military had internal backing from rebel factions that benefited from a 2020 peace deal and from veterans of Mr Bashir's government who returned to the civil service following the coup.
The coup put the army back in charge, but it faced weekly demonstrations, renewed isolation and deepening economic woes.
In recent months, Hemedti has said the 2021 coup was a "mistake" that failed to bring about change in Sudan and reinvigorated remnants of Mr Bashir's regime.
General Burhan, a career soldier from northern Sudan who rose through the ranks under Mr Bashir, maintained that the coup was "necessary" to bring more groups into the political process.
ABC/Wires