The United Nations humanitarian coordinator in Sudan warned on Monday that the humanitarian crisis in the country was turning into a "full blown catastrophe" and that the risk of spillover into neighboring countries was worrisome. "It has been more than two weeks of devastating fighting in Sudan, a conflict that is turning Sudan humanitarian crisis into a full blown catastrophe," Abdou Dieng, Resident and Humanitarian Coordinator in the country, told a briefing of member states via video link. Dieng added that civilians were taking refuge in parts of Sudan less affected by fighting or fleeing to neighboring countries. "The regional spillover effect of the crisis is a serious concern," he said. More than 800,000 people may flee Sudan as a result of fighting between military factions, including many who had already come there as refugees, another UN official said on Monday. "Without a quick resolution of this crisis we will continue to see more people forced to flee in search of safety and basic assistance," Raouf Mazou told a member state briefing in Geneva. "In consultation with all concerned governments and partners weve arrived at a planning figure of 815,000 people that may flee into the seven neighboring countries." The estimate includes around 580,000 Sudanese, he said, with the others existing refugees from South Sudan and elsewhere. So far, he said some 73,000 people have already fled to Sudans neighbors - South Sudan, Chad, Egypt, Eritrea, Ethiopia, Central African Republic and Libya. UN aid chief Martin Griffiths will visit Sudan on Tuesday, said Ramesh Rajasingham of the UN Office for the Coordination of Humanitarian Affairs. Griffiths was in Nairobi, Kenya, on Monday to discuss the situation in Sudan, which he described as "catastrophic." "We need to find ways to get aid into the country and distribute it to those in need," Griffiths wrote on Twitter.