The situation in Myanmar is a "textbook example of ethnic cleansing", the United Nations rights chief said Monday, as Washington condemned a surge in violence that has sent more than 300,000 Rohingya Muslims fleeing for Bangladesh.
Hours after the UN warning, the Security Council announced it would meet Wednesday to discuss the violence, prompting an ongoing exodus of Rohingya into neighbouring Bangladesh.
Refugees fleeing the unrest have brought stories of entire villages burned to the ground by Buddhist mobs and Myanmar troops.
Myanmar's de facto civilian leader Aung San Suu Kyi, a Nobel peace prize laureate, has faced strong international criticism over an army crackdown on the Muslim minority, which began when Rohingya militants ambushed security forces in Rakhine State on August 25.
On Monday the UN human rights chief, Zeid Ra'ad Al Hussein, accused Myanmar of waging a "systematic attack" on Rohingya civilians and warned that "ethnic cleansing" seemed to be under way.
"Because Myanmar has refused access to human rights investigators the current situation cannot yet be fully assessed, but the situation seems a textbook example of ethnic cleansing," he told the UN Human Rights Council.
The stateless Rohingya have faced decades of persecution in Myanmar, where they are regarded as illegal immigrants.
The White House broke its silence on the crisis on Monday, saying it was "deeply troubled" by attacks by both sides, including the militant ambushes in Rakhine.
We "reiterate our condemnation of those attacks and ensuing violence", Press Secretary Sarah Huckabee Sanders said, without directly accusing the Myanmar military of carrying out a crackdown.
'We will follow'
The UN special rapporteur on human rights in Myanmar has said the latest violence may have left more than 1,000 dead, most of them Rohingya.
The UN refugee agency says at least 313,000 Rohingya have now arrived in Bangladesh from Rakhine State since August 25, about a third of the total population of 1.1 million.
The actual figure could be even higher: The UN said many new arrivals are still on the move and are therefore left out of the calculations.
Most have walked for days, and the United Nations says many are sick, exhausted and in desperate need of shelter, food and water.
Safura Khatun, 60, was among the hundreds who crossed into Bangladesh on Monday.
She told AFP it had taken her 15 days to reach Bangladesh from her village south of Maungdaw, where her husband and three sons had been killed.
"I had only water for the last five days," she said, rocking on the spot in a yellow headscarf.
"I don't know what I will do here. We will follow the others."
A further 27,000 ethnic Rakhine Buddhists as well as Hindus have also fled violence that has gripped northern Rakhine, where international aid programmes have been severely curtailed.
As concern grows over the crisis, Britain and Sweden requested an urgent meeting of the UN Security Council, due on Wednesday.
"It's a sign of the significant worry that Security Council members have about the situation that is continuing to deteriorate for the many Rohingyas who are seeking to flee Rakhine state," British Ambassador Matthew Rycroft told reporters.
On Monday it emerged that the Dalai Lama had joined fellow Nobel peace laureates Malala Yousafzai and Archbishop Desmond Tutu in urging Suu Kyi to intervene.
"Questions that are put to me suggest that many people have difficulty reconciling what appears to be happening to Muslims there with Myanmar's reputation as a Buddhist country," the Tibetan spiritual leader wrote in a letter to Suu Kyi shortly after the latest fighting broke out.
"I appeal to you and your fellow leaders to reach out to all sections of society to try to restore friendly relations throughout the population in a spirit of peace and reconciliation."
'Appalled'
Refugee camps and makeshift settlements near the border with Myanmar were already hosting hundreds of thousands of Rohingya before the latest influx, and are now completely overwhelmed.
That has left tens of thousands of new arrivals with no shelter from the monsoon rains.
Dhaka, which initially tried to block the Rohingya from entering, said Monday that it would start registering all new arrivals.
The Bangladesh government plans to build a huge new camp that will house a quarter of a million refugees.
But it remains unclear when or whether they will be able to return.
The UN's Zeid said he was "appalled" by reports that Myanmar security forces were laying mines near the border to stop Rohingya returning.
Three Rohingya are reported to have been killed by a mine, and at least two more have lost limbs. One of the victims was a young boy.
On Sunday, the Arakan Rohingya Salvation Army, the militant group whose attacks sparked the latest crackdown, declared a unilateral ceasefire to allow aid to reach the increasingly desperate refugees.
There was no immediate response from Myanmar's military, but on Saturday authorities said they would set up three relief camps in Rohingya-majority areas.