More than 80 people have been killed in two days of ongoing clashes in Sudan's restive Darfur, doctors said Sunday, just over two weeks since a long-running peacekeeping mission ended operations.

The violence is the most significant fighting reported since the signing of a peace agreement in October, which observers hoped would end years of war that has left the vast western region awash with weapons.

The fighting reportedly pitted Arab against non-Arab tribes in West Darfur's capital El Geneina, and is thought to have started as a local dispute before escalating into broader disputes between militias.

"The death toll from the bloody events that occurred in El Geneina, the capital of West Darfur State, has risen since Saturday morning... to 83 dead, and 160 wounded including from the armed forces," the Central Committee of Sudan Doctors said.

The United Nations -- a long-running presence in the nation -- also expressed deep concerns on Sunday over the violence.

Sudanese authorities have imposed a state-wide curfew in West Darfur, while the Khartoum government dispatched a "high-profile" delegation to help contain the situation.

Citing the doctors' union, the state-run SUNA news agency said casualties were likely to increase as fighting continues.

The union's local branch also said health facilities must be secured and transport made available. 

On Sunday, the head of Sudan's ruling body, army chief General Abdel Fattah al-Burhan, met top security chiefs to discuss the violence.

They decided to send reinforcements to the region to secure civilians and key infrastructure, the cabinet announced on Twitter.

The Sudanese Professionals Association, an umbrella group which spearheaded protests against ousted president Omar al-Bashir, said the violence hit camps for people already displaced by conflict.

"These events showed that the spread of weapons across Sudan, and especially in Darfur, are the main reasons for the deteriorating situation," it said in a statement.

- Peacekeeping mission over -

On December 31, the hybrid United Nations African Union Mission in Darfur (UNAMID) formally ended its 13 years of operations in the region.

It plans a phased withdrawal of its approximately 8,000 armed and civilian personnel within six months.

The Sudanese government "will take over responsibility for the protection of civilians" in Darfur, UNAMID said as its mandate ended.

Fearing deadly violence, Darfur residents held protests in late December against UNAMID's departure.

Also in late December, clashes in South Darfur state left at least 15 people dead and dozens wounded, prompting the government to send troops to the area.

On Sunday, the UN secretary-general's spokesman Stephane Dujarric called on Sudanese authorities to "bring an end to the fighting".

"Escalating inter-communal violence has resulted in scores of deaths and injuries, the displacement of nearly 50,000 people and the destruction of property," he said in a statement.

Darfur endured a bitter conflict that erupted in 2003, leaving roughly 300,000 people dead and 2.5 million displaced, according to the UN.

The fighting erupted when ethnic minority rebels rose up against the Arab-dominated government in Khartoum, which responded by recruiting and arming a notorious Arab-dominated militia known as the Janjaweed.

The main conflict has subsided over the years but ethnic and tribal clashes still flare periodically, largely pitting nomadic Arab pastoralists against settled farmers from non-Arab ethnic groups. 

The violence often centres on land ownership and access to water.

- Root causes 'not addressed' -

Sudan is undergoing a rocky political transitional after Bashir's April 2019 ouster.

Bashir, who is currently in custody in Khartoum, is wanted by the International Criminal Court for alleged genocide and war crimes in Darfur perpetrated more than a decade ago.

The transitional government, a power sharing arrangement comprised of generals and civilian figures, signed an October peace agreement with rebel groups in Sudan's main conflict zones, including Darfur.

But two groups refused to join the recent peace deal, including the Sudan Liberation Movement (SLM) faction led by Abdelwahid Nour, which is believed to maintain considerable support in Darfur.

The Sudanese Professionals Association said the violence in West Darfur shows the "deficiencies" of the peace agreement, which they said did not address the roots of the crisis in the region.