More than 100 civilians, among them at least 20 children and a medical team, have been killed in a series of attacks beginning towards the end of last week in Sudan's western Darfur region, the UN has said.

The assaults – on the city of el Fasher and two nearby camps housing people forced from their homes by the civil war – have been blamed on the paramilitary Rapid Support Forces (RSF). It has said reports of atrocities were fabricated.

The camps, Zamzam and Abu Shouk, provide temporary homes to more than 700,000 people, many of whom are facing famine-like conditions.

News of the attacks comes on the eve of the second anniversary of the civil war between the RSF and the army.

The UN's humanitarian co-ordinator in Sudan, Clementine Nkweta-Salami, said she was "appalled and gravely alarmed" by reports of what had happened.

"This represents yet another deadly and unacceptable escalation in a series of brutal attacks on displaced people and aid workers," she added in a statement.

Aid organisation Relief International said nine of its workers "were mercilessly killed, including doctors, referral drivers and a team leader" in the attack on Zamzam.

The charity, which said it was the last provider of critical health services in the camp, alleged RSF fighters were to blame.

"We understand that this was a targeted attack on all health infrastructure in the region to prevent access to healthcare for internally displaced people.

"We are horrified that one of our clinics was also part of this attack - along with other health facilities in el-Fasher."

In a statement released on Saturday, the RSF said it was not responsible for attacks on civilians and that scenes of killing in Zamzam were staged to discredit its forces.

Contacting the BBC on Sunday morning, one Zamzam resident who works at a community kitchen providing food for those in the camp, said the situation was "extremely catastrophic".

"We've lost a large number of young people, those who were working in the community kitchen have been killed, and the doctors who were part of the initiative to reopen the hospital were also killed," Mustafa, 34, said in a WhatsApp audio message.

"My uncle and my cousin were killed. People are wounded, and there is no medicine or hospital to save them - they are dying from bleeding.

"The shelling is still ongoing, and we are expecting more attacks in the morning."

He added that all routes out of the camp were closed and it was "surrounded from all four directions".

Another resident, Wasir, said things were "extremely dire".

"There is nothing left in Zamzam. A large number of civilians have fled, and we are still trying to leave, but we haven't succeeded all the roads are blocked, and we have children with us.

"Death is everywhere. As I speak to you now from inside the trench, there is shelling happening."

The war - a power struggle between the army and the RSF - has created the world's largest humanitarian crisis, forcing more than 12 million people from their homes and pushing communities into hunger.

It began on 15 April 2023, after the leaders of the army and RSF fell out over the political future of the country.

El-Fasher is the last major town in Darfur under army control and has been under siege by the RSF for almost a year.