They were the first clashes between the forces since they formed an alliance in 2019 and rose out of a long-running tussle for power.

US secretary of state Antony Blinken is among those around the world who have urged a ceasefire after a US convoy came under fire.

Both sides have offered truces in previous days, but the fighting has not stopped.

Here is what you need to know about the conflict.

Who are the main players?

On one side you've got Sudan's army, headed by General Abdel Fattah al Burhan.

He has been the country's de facto president since a military coup in October 2021.

On the other is paramilitary group the RSF, the partner-turned-rival of the military.

The RSF is led by General Mohamed Hamdan Dagalo, better known as Hemedti. He is the deputy head of Sudan's ruling Sovereign Council.

The two sides came together to oust former leader Omar al Bashir in 2019 but there have been long-running disagreements over how the country should be run.

Since the clashes started, both sides have claimed to be in control of strategic locations, including the presidential palace, airports and air bases.

Speaking to Sky News, General Burhan said he was open to negotiations as the fighting continues.

"If negotiations will restore the country and are fair then it's possible," he added.

The RSF also issued a statement saying it was waging a continuing battle to restore "the rights of our people".

However, the fighting has continued.

Why has violence erupted now?

The recent violence erupted out of tensions over the transition from military to civilian rule.

Things escalated in the days before as RSF troops were deployed around the country.

In a rare statement, the army said the mobilisation represented a "clear violation of law".

Central to the tension was a disagreement between the army and the paramilitary over how and when the RSF should be integrated into the military.

The army wanted the transition to happen within two years while the RSF said it would take 10 years.

The merger was a key condition of a framework deal agreed in December that would have seen power shifted to civilians.

The agreement was supposed to be signed on 1 April, but it was delayed because of failed talks.

Read more:
Why tensions in Sudan could escalate into 'all-out civil war'
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Where is the fighting happening?

The fighting began at a military base south of the capital Khartoum, with both sides accusing the other of initiating attacks.

Clashes then spread across the city, including around the military's headquarters, the airport and the presidential palace.

Witnesses have reported gunfire in many parts of the country, including heavy exchanges of gunfire in the northern city of Merowe and clashes in the Darfur cities of El Fasher and Nyala.

Several countries, including the UK, have extracted their diplomats but many civilians with foreign or dual citizenship say they cannot escape the fighting.

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UN secretary-general Antonio Guterres has strongly condemned the outbreak of fighting and appealed to both leaders to immediately cease hostilities, restore calm and begin a dialogue to resolve the crisis.

Meanwhile, the World Health Organization (WHO) says there have been three attacks on healthcare facilities in Sudan since the outbreak of fighting.

The International Federation of Red Cross (IFRC) has warned that continued disruption to the healthcare system could result in its collapse and that providing aid around the Sudanese capital was "almost impossible".

Who are the RSF?

The RSF is made up of about 100,000 troops and evolved from so-called janjaweed militias that fought in the Darfur conflict in the 2000s.

The RSF has long been accused of atrocities linked to the Darfur conflict.

In 2017, a law legitimising the RSF as an independent security force was passed.

Transition to democracy

Former president Omar al Bashir was ousted in 2019 following months of protests against his three-decade authoritarian rule.

He was convicted of corruption and money laundering and accused by the International Criminal Court of war crimes and genocide, linked to the bloody conflict in Darfur.

A joint military-civilian government was established after he was toppled but that was overthrown in the 2021 coup.

The coup put the army back in charge, but it faced weekly demonstrations, renewed isolation and deepening economic woes.