(CNN) -- The United Nations humanitarian chief urged Sudan to allow aid workers into a Darfur refugee camp that has been closed for nearly two weeks, limiting access to 80,000 displaced people.
Sudanese authorities prevented aid agencies from entering Kalma camp and its surrounding areas after violence broke out earlier this month. The closure came despite reassurances that restrictions had not been imposed.
"I am extremely concerned about the welfare of the IDPs at Kalma camp, to whom we have not been able to deliver relief for 13 days," John Holmes, U.N. Under-Secretary-General for Humanitarian Affairs, said Friday.
"Deliveries of food and fuel for water pumps have for example not been possible. Sanitation is also a major concern as it is the middle of the rainy season. Many thousands of IDPs from Kalma remain unaccounted for."
Darfuris who live at the camp rely on aid groups for food, water, health, nutritional support and shelter.
Tensions escalated at the camp last week after thousands of displaced Darfuris took to the streets to protest what they called unrepresentation in the latest round of peace talks in Doha, Qatar.
Officials demanded that the joint U.N.-African Union peacekeeping force, UNAMID, hand over six local leaders who sought protection with the peacekeepers. The peacekeeping force said it will not do so unless the government pledges to give them a fair trial
The United Nations Office for the Coordination of Humanitarian Affairs says constraints on aid agencies in the region have been steadily increasing since March 2009, when 11 international aid groups were expelled from Darfur.
Two staff members from the International Organization for Migration were also expelled last month.
"The United Nations has been in close contact with the relevant Sudanese authorities to restore access to both Kalma and Eastern Jebel Marra, but until today progress has not been forthcoming," Holmes said. "If access is not urgently restored, the situation risks deteriorating rapidly."
Darfur, a province of Sudan, has suffered the worst humanitarian crisis in the world, according to aid groups.
United Nations officials estimate that 300,000 people have died in the past seven years and more than 3 million displaced amid fighting between rebels and government forces.
The Darfur conflict started when two rebel groups -- the Sudan Liberation Army and Justice and Equality Movement -- started attacking the government in 2003. The groups accused Khartoum of favoring Arabs and oppressing black Africans.
Government forces have been backed by the Janjaweed, a militia accused of murdering, raping, and burning homes in Darfur