Rohingya Muslims walk to the shore after arriving on a boat from Myanmar to Bangladesh in Shah Porir Dwip, Bangladesh, Thursday, Sept. 14, 2017 (Photo: AP)
The number of Rohingya who have fled Myanmar for Bangladesh to escape ethnic unrest hit 389,000 on Thursday and the United Nations warned of a looming "worst case scenario" with all of the Muslim minority group trying to leave.
The figure rose 10,000 in 24 hours, indicating the Rohingya crisis remains acute.
Relief agencies are struggling to contain a humanitarian crisis unfolding around the Bangladesh border town of Cox's Bazar with 10,000-20,000 people crossing over each day.
"When we provided the first number of people coming, we talked about 79,000 or 80,000 and within two and half weeks we have 400,000," Mohammed Abdiker Mohamud, an International Organization for Migration (IOM) director, said.
"You have to have the best estimate, the best case scenario, which is no more people will come. We have to estimate the worst case scenario where everybody moves out," he added.
"We cannot just put our heads in sand say that everything will be OK," he said.
"Unless a political solution is found there is a possibility that the entire Rohingya community may come to Bangladesh," he told AFP later.
There were an estimated 1.1 million Ronhingya in Rakhine state, who have endured decades of persecution in Buddhist-dominated Myanmar.
At least 300,000 had fled to Bangladesh before the latest crackdown started on August 25, following attacks by Rohingya militants on police targets.
The exodus since has taken the overall figure of those who have quit Myanmar to at least 700,000.
Other UN agencies have sounded the alarm over conditions in Bangladesh which is struggling to cope.
The camps around Cox's Bazar were ill-equipped even before the latest violence erupted.
The UN children's agency, UNICEF, says 60 percent of the new arrivals are children.
"There are acute shortages of everything, most critically shelter, food and clean water," said Edouard Beigbeder, UNICEF's representative in Bangladesh, in a statement.
"Conditions on the ground place children at risk of high risk of water-borne disease. We have a monumental task ahead of us to protect these extremely vulnerable children."
The IOM's Mohamud, who was part of a UN team that visited the Rohingya camps in recent days, said the crisis has caught the UN, international agencies and Bangladesh government by surprise.
Because existing camps were already overflowing, new arrivals have made makeshift encampments around them.
"Let's be honest. Nobody expected you are going to get 400,000 people cross the border into Bangladesh, so nobody was ready, with food, shelter, health facilities."
He said the international community has to provide more help "quickly".
"We need to see more engagement and more support, There is a need for help," said.
While the Myanmar military says Rohingya militants are behind the violence, UN Secretary General Antonio Guterres has called the military crackdown ethnic cleansing.
The UN Security Council on Wednesday called for "immediate steps" by Myanmar to end the violence.