The United Nations’ top humanitarian official in Sudan says the paramilitary group at war with the military in Sudan is preventing life-saving aid from reaching many people in the famine-hit Darfur region. Clementine Nkweta-Salami said Monday that the Rapid Support Forces have imposed “obstruction, undue interference and operational restrictions” on aid supplies to areas under their control. There was no immediate comment from the RSF, which controls most of the sprawling western region. The conflict has killed more than 28,000 people, forced millions to flee their homes and left some families eating grass in an attempt to survive.