At least two people were killed when Sudan's paramilitary Rapid Support Forces attacked a camp for displaced people in the North Darfur region, activists said on Monday.
The Zamzam camp, south of the regional capital El-Fasher, was hit by heavy rocket and artillery fire from the RSF on Sunday morning, said the local resistance committee in El-Fasher.
The "indiscriminate" attack killed at least two people and wounded a dozen others, said the committee, one of hundreds of volunteer groups coordinating aid in Sudan.
The northeast African country has been gripped by a war between the regular army and RSF that has killed tens of thousands and displaced more than 11 million since April last year.
Both sides face accusations of war crimes, including targeting civilians, shelling residential areas, and blocking or looting aid.
UN humanitarian chief Tom Fletcher, after visiting Sudan and neighbouring Chad last week, called for immediate international action to address the crisis.
"It is a tough situation out there, the biggest humanitarian crisis in the world. And I've been talking to local people to host communities," Fletcher said in a weekend statement.
Nearly 26 million people -- about half the population -- face the threat of mass starvation in Sudan as both warring sides have been accused of using hunger as a weapon of war.
"These numbers are staggering, and we cannot turn our backs," Fletcher said.