Thousands of displaced people have surged towards already overcrowded camps in western Myanmar, the UN said on Saturday, after vicious new communal violence that has left dozens dead.
Seething resentment between Buddhists and Muslims erupted this week in a wave of fresh unrest in Rakhine state, prompting international warnings the unrest imperils the nation's nascent reform process.
The official death toll stood at 67, about half of whom were women, according to a state spokesman.
Tens of thousands of mainly Muslim Rohingya are already crammed into squalid camps around the state capital, Sittwe, after deadly violence in June and the UN on Saturday said the latest fighting had caused a further 3200 to make their way towards the shelters.
"An additional 2500 are reportedly on their way," said Vivian Tan, spokeswoman for the UN's refugee agency.
Rakhine government spokesman Win Myaing on Friday conceded authorities were struggling to provide relief to an estimated 3000 Rohingya who had escaped in boats as violence engulfed their townships and had docked on an island near Sittwe.
"The displaced are still on the island," he told AFP on Saturday.
He said troops were "taking control" of potential hotspots, adding the situation was now "calm" after security forces were deployed to the affected areas on October 21.
More than 150 people have been killed in the state since June, according to the authorities, who have imposed emergency rule in the face of continued tension in the region.
President Thein Sein has been widely praised for overseeing sweeping reforms in the former junta-ruled nation, including the release of hundreds of political prisoners and the election of opposition leader Aung San Suu Kyi to parliament.
But the fighting has posed a threat to the reforms.
"The vigilante attacks, targeted threats and extremist rhetoric must be stopped," a spokesman for UN Secretary-General Ban Ki-moon said in a statement on Friday.
"If this is not done... the reform and opening-up process being currently pursued by the government is likely to be jeopardised."
Myanmar's 800,000 Rohingya are seen as illegal immigrants from neighbouring Bangladesh by the government and many Burmese who call them "Bengalis".
The stateless Rohingya have long been considered by the UN as one of the most persecuted minorities in the world.