At least 40 people in Sudan have been killed in a drone strike that targeted a funeral that was taking place outside the army-held city of el-Obeid in North Kordofan state, officials and activists say.

They blamed the paramilitary Rapid Support Forces (RSF) for Monday's attack on al-Luweib village as mourners had gathered in a tent. The RSF has not yet commented.

Many reportedly died before getting to hospital in el-Obeid, a strategic city that connects the capital, Khartoum, to the western region of Darfur.

Fighting has intensified in this oil-rich Kordofan area and around 20,000 people fled to el-Obeid last week after the RSF captured Bara town, 30km (18 miles) north of the city.

The town fell at the same time as the city of el-Fasher, which had been the army's last stronghold in Darfur.

There have since been reports of mass killings, sexual violence, abductions and widespread looting in el-Fasher by RSF fighters.

The UN said summary executions of civilians by RSF fighters had also also been reported in Bara.

Such atrocities could amount to war crimes and crimes against humanity, the International Criminal Court (ICC) has warned.

The RSF leader has promised to investigate "violations" but his paramilitary group has denied widespread allegations that the killings in el-Fasher are ethnically motivated and follow a pattern of the Arab paramilitaries targeting non-Arab populations.

The ICC's statement came as a global group of food security experts confirmed on Monday that el-Fasher residents were suffering from famine following the RSF's 18-month siege of the city.

The UN-accredited Integrated Food Security Phase network (IPC) also said the city of Kadugli in South Kordofan state was in the most catastrophic stage of hunger.

The city, nearly 300km south of el-Obeid, has been also surrounded and starved of supplies by the RSF.

UN chief António Guterres has called for an immediate halt to the violence in Sudan, warning that the humanitarian crisis is rapidly worsening.

"The horrifying crisis in Sudan... is spiralling out of control," he said on the side-lines of a summit in Doha.

"El-Fasher and the surrounding areas... have been an epicentre of suffering, hunger, violence and displacement - and since the Rapid Support Forces entered el-Fasher last weekend, the situation is growing worse by the day," AFP news agency quotes him as saying.

Guterres urged the army and the RSF to come to the negotiating table and "bring an end to this nightmare of violence".

A Sudanese government source has told AFP that the authorities are considering a US proposal for a truce.

Washington - along with other states - has been pushing for a ceasefire and a roadmap to end the conflict.

There have been several rounds of peace talks in Saudi Arabia and Bahrain - but they have failed - and both sides have shown an unwillingness to agree to a ceasefire.

The North Kordofan Resistance Committee, a volunteer aid group, said the attack on the village, which is 15km east of el-Obeidz, happened on Monday.

Mohamed Ismail, North Kordofan's humanitarian aid commissioner, told the Sudan Tribune new website: "Drones belonging to the Rapid Support Forces militia attacked citizens who were at a funeral, resulting in the death of 40 people and the injury of dozens."

Last week, the UN said el-Obeid was already struggling to cope with the influx of those fleeing from Bara.

Since the civil war erupted between the army and RSF in April 2023, more than 150,000 people have died about 12 million have fled their homes in what the UN has called the world's largest humanitarian crisis.