The United Nations has urged Sudanese authorities to allow humanitarian organisations access to a Darfur refugee camp which was closed to aid agencies for more than a week following an outbreak of violence.
UN spokesman Martin Nesirky said about 50,000 people are still believed to be in Kalma camp in South Darfur and several thousand took refuge outside a community police centre run by the joint UN-African Union peacekeeping force.
"We are concerned about the shortages of food and fuel. Deliveries have stopped and fuel for water pumps has run out. And so, obviously, sanitation is a major concern, because it's the middle of the rainy season," Mr Nesirky said.
"The government must resume full humanitarian access to Kalma and to surrounding areas where displaced people have fled," he said.
The Save Darfur Coalition called the Sudanese government's behaviour "atrocious" and said its denial of humanitarian aid and threat to relocate the Kalma camp was leaving families even more vulnerable to hunger and disease.
The coalition urged the United States and the international community to pressure the government to allow immediate, unimpeded access for UN agencies and humanitarian organisations.
Frank Donaghue, chief executive officer of Physicians for Human Rights, warned that "the camps aren't capable of sustaining life. Without food, water and medicine, the people in the camps will begin to die, just as surely as if the government were attacking them with conventional weapons," he said in a statement.
Samuel Hendricks, spokesman for the UN Office for the Co-ordination of Humanitarian Affairs in Darfur, said late last week that at least five people died and thousands fled the camp following demonstrations that became fatal.
Mr Nesirky said there were also recent reports of sporadic firing in the camp.
The commander of the UN-AU force, known as Unamid, visited Kalma camp over the weekend and the force stepped up patrols in and around Kalma "and is on high alert," he said.