The Emergency Lawyers said Monday's air strike also left hundreds injured in Kabkabiya, a town about 180 kilometres (112 miles) west of El-Fasher, the state capital that has been under siege from the paramilitary Rapid Support Forces (RSF) since May.

Tens of thousands have been killed and millions displaced in a 20-month war between the RSF and Sudan's army that has left the northeast African country on the brink of famine, according to aid agencies.

"The air strike took place on the town's weekly market day, where residents from various nearby villages had gathered to shop, resulting in the death of more than 100 people and injury of hundreds, including women and children," said the lawyers group, which has been documenting human rights abuses during the conflict.

In footage sent to AFP purporting to show aftermath of Monday's strike, people were seen sifting through rubble as the charred remains of children lay on scorched ground.

The footage was supplied by civil society group the Darfur General Coordination of Camps for the Displaced and Refugees and AFP has not been able to verify its accuracy.

The lawyers group said in a separate incident on Monday evening three neighbourhoods were hit with barrel bombs in Nyala, the capital of South Darfur, without reporting casualties.

Darfur, a region the size of France, is home to around a quarter of Sudan's population but more than half of its 10 million are displaced.

A UN-backed report in July said famine had taken hold in a major refugee camp in North Darfur after a months-long RSF siege disabled nearly all trade and aid access.

- 'Escalation campaign' -

The lawyers group said they "condemn in the strongest terms the horrendous massacres committed by army air strikes" in Kabkabiya.

They flagged another incident in North Kordofan state in which drone that had crashed on November 26 exploded on Monday evening, killing six people.

They said recent strikes across Sudan were part of an "escalation campaign... deliberately concentrated on densely populated residential areas", contradicting claims by warring parties that they only target military objectives.

Both the army and the RSF have been accused of indiscriminately targeting civilians and deliberately bombing residential areas.

Last week, UN humanitarian chief Tom Fletcher called for immediate international action to address Sudan's deepening crisis.

Fletcher said he had heard "heart-rending stories" from refugees fleeing the conflict during a recent visit.

Nearly 26 million people -- about half the population -- face the threat of starvation, with both sides accused of using hunger as a weapon of war.

"These numbers are staggering, and we cannot turn our backs," Fletcher said.