A surging number of hungry refugees are fleeing fighting between Sudanese troops and ethnic rebels, with some reduced to foraging in the wild, the United Nations said on Monday. 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 UN humanitarian agency (OCHA) said in its weekly bulletin. The refugees are fleeing fighting between Sudanese troops and the rebel Sudan People\'s Liberation Movement -- North (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 the South 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. Yida refugee camp is a key destination for people fleeing the fighting in South Kordofan, which began in June last year. \"Some new refugees from South Kordofan who arrived in South Sudan told humanitarian organisations that they were relying on wild food, because they could not plant because of the fighting and limited commercial supplies of food,\" OCHA said. Sudan has cited security concerns in severely controlling access for foreign relief agencies to South Kordofan and Blue Nile, where a similar conflict began in September. The UN and others have warned for months that aid agencies need access throughout the area -- including to rebel-held zones -- to properly assess people\'s needs and distribute assistance to prevent a worsening of the humanitarian situation. The insurgents fought alongside southern rebels during the civil war which ended in 2005, before the South\'s independence last July. They deny Sudan\'s allegation that they are supported by South Sudan. There are now more than 114,000 Sudanese refugees in South Sudan, the UN says.