Violence pitting area Muslims against Buddhists in Rakhine, along Myanmar's western coast, left at least 89 people dead last month. The United Nations estimates at least 35,000 people were displaced by violence that left entire villages destroyed.
Jens Laerke, a spokesman for the U.N. Office for the Coordination of Humanitarian Affairs, told U.N. Radio the situation in Rakhine was unstable.
"The situation is still very, very volatile, it's very tense," he said. "The government is doing its very best to keep the situation under control but it's still very fragile."
The government in Myanmar, through its official New Light of Myanmar news agency, had said the situation in Rakhine was "put under control." At least 1,000 people have been arrested since June in connection with the violence.
Laerke said it was important that international human rights groups gain access to Rakhine to get a better understanding of the situation.
"What we know from the preliminary findings is that (displaced communities) need food, shelter and other basic necessities," he said.