Ten aid workers have gone missing in South Sudan’s Yei town in unclear circumstances, a UN official said on Thursday. Alain Noudehou, the UN Humanitarian Coordinator for South Sudan, said a convoy of UN and other aid workers had been heading to Tore from Yei, in Central Equatoria region. Their whereabouts and well-being were now unknown. “We are deeply concerned about the whereabouts of these humanitarian workers and are urgently seeking information about their well-being,” Noudehou said. Aid workers are often targeted by armed groups operating in South Sudan which has been in the grip of a war between supporters of President Salva Kiir and those of his former deputy Riek Machar since 2013. Tens of thousands of people, including nearly 100 relief workers, have been killed. Noudehou said those missing were all South Sudanese, with one working for the humanitarian office , two from UNICEF, one from South Sudanese Development Organization, two from aid group ACROSS, three from Plan International and one from Action Africa Help. On Monday, the International Committee of the Red Cross said it had suspended operations in Leer after their field base was shot at on April 10. It evacuated its staff to Juba. In mid April, South Sudan’s rebels said they had released seven aid workers detained for nearly three weeks in the Central Equatoria region on accusations of spying for the government. An aid worker was also killed when gunmen shot at his agency vehicle near the northern town of Bentiu. Both rebels and the government forces stand accused of targeting humanitarian workers and sometimes blocking access to relief and hijacking food and other aid.