More than 360,000 people have fled fighting between the Pak military and Taliban in little more than a week and that number could double by the end of the year, UN officials warned Monday. Piling into vehicles or leaving on foot with hastily packed belongings, frightened civilians are trying to escape the military bombardments of Islamist extremists who are dug into three northwest districts. "We have a major displacement crisis on our hands... The situation is very fluid. As we speak, people are on the move," said Manuel Bessler, the head of UN's Office for the Coordination of Humanitarian Affairs (OCHA) in Pakistan. "The figure as of (Sunday) evening is 360,675 individuals who are registered," he said. Bessler warned that the number of people fleeing the districts of Swat, Buner and Lower Dir was likely higher as many people do not register. "We have to be prepared to assist up to 800,000 in addition to the already pre-existing 500,000," he said. That figure was a rough prediction from now until December, he stressed, to allow the UN to plan humanitarian relief. More than 500,000 people have already been displaced from Pakistan's northwest, where military offensives against Islamist militants have been conducted over at least six years. A spokeswoman for the United Nations refugee agency UNHCR said 360,600 people had been registered in and outside camps from Swat, Buner and Lower Dir since May 2. Ariane Rummery said the provincial government in North West Frontier Province, with the help of UNHCR, had set up 29 registration points. . Many of the displaced prefer to live with relatives or rent homes, rather than stay in the basic and crowded camps. A local Pakistani government official working at the emergency response unit in provincial capital Peshawar said half a million had fled "since the offensives" but was not able to provide an exact date. OCHA expressed concern for civilians who remain in the conflict areas, where fighter jets and helicopter gunships are bombarding militant positions. "People find themselves, beside the danger of warfare, boxed into a ghost town or ghost area where they are completely on their own without any support," Bessler said. Food was scarce and hospitals underequipped, he added. People streaming south say scores of civilians have been killed in the army offensives, but Bessler said figures were difficult to compile because of lack of access to the conflict zones. "We are very concerned that the warring parties have to respect protection of civilians, or non-combatants, and given the warfare which is very often these days happening in urban areas," he said. Pakistani security forces have conducted operations against militants in parts of North West Frontier Province over the past two years, on top of six years of battles in the surrounding semi-autonomous tribal belt on the border with Afghanistan.