A surging number of hungry refugees are fleeing fighting in Sudan where some are reduced to foraging in the wild, the UN said Monday, amid new allegations of Sudanese air strikes.In South Kordofan state, where insurgents deny being backed by South Sudan, a Sudanese air raid killed a mother and two children, the rebel Sudan People's Liberation Movement-North (SPLM-N) said.Air raids also continued over the weekend against South Sudanese frontline positions, the South Sudanese army said, despite an African Union order last week that the two nations cease border hostilities within 48 hours.Sudan denied bombing in South Kordofan or South Sudan.There has been "a notable increase in the number of new arrivals" who have crossed the border from South Kordofan into South Sudan's Unity state, the United Nations humanitarian agency (OCHA) said in its weekly bulletin.The refugees are fleeing fighting between Sudanese troops and the SPLM-N, it said.An average of 234 people crossed into the South every day in April, compared with 84 per day in February and March, the bulletin added.The most serious border clashes yet between Sudan and South Sudan raged in April around the Heglig oil region, which is part of South Kordofan state.South Sudan occupied the Heglig area for 10 days and Sudan carried out air strikes over the border in Unity state.Elsewhere in South Kordofan, SPLM-N rebels besieged the town of Talodi into early April and, after a lull, fighting in the area intensified later in the month."Newly arrived refugees told UNHCR that food shortages, concerns that they may not be able to reach Yida with the rainy season approaching and intense fighting in their places of origin have prompted them to move to Yida," said the OCHA bulletin, covering the week to April 22.Some reported "that they were relying on wild food" because fighting prevented them from planting and there was limited food for sale, it said.