Mark Lowcock, UN under-secretary-general for humanitarian affairs, while appealing for access to the population in northern Rakhine, said the situation was "unacceptable" and the flow out of Myanmar has not stopped yet.
Bangladesh last month said Myanmar drones and choppers violated its airspace repeatedly and installed landmines on its borders to prevent return of Rohingyas.
Still villagers say Rohingya are still attempting to leave and many are gathered on the beaches just across the water from Bangladesh waiting for a chance to leave the country. The Rohingya, a Muslim minority, have been forced to flee the state following a violent crackdown by Myanmar authorities since the end of August.
The Trump administration has promised USD32 million in assistance - United States dollars 28 million of which will go to Bangladesh, where roughly half-a-million Rohingyas are presently based.
Unlike most of the European countries, which are not signatories to the 1951 International Convention on Refugees and are shutting the doors on refugees from West Asia, Bangladesh hosted the Rohingyas, he observed.
Facing worldwide pressure, Myanmar's de-facto leader Aung San Suu Kyi this week sent a senior representative to Dhaka for talks. The diplomats, which also included the U.S., French and German ambassadors to Myanmar, negotiated a number of conditions with the Myanmar government and Border Police Guard: that they visit an isolated Rohingya village, that police stay back when they speak with villagers and the people they speak with be protected from reprisals.
"Rohingyas are facing ethnic cleansing in Myanmar possibly due to a free economic zone that is likely to come up in their region".
"A rapid response from donors to this response plan is essential if the humanitarian organisations are to move ahead with critical activities to save lives, and provide protection to Rohingya refugees in Bangladesh", Watkins said.
In a strong message to the world community, Bangladesh has warned that the ongoing "ethnic cleansing" in Myanmar should not only be viewed from the humanitarian angle, but should also be seen as a security threat with the potential to destabilize not only Myanmar or Bangladesh, but the entire Asian continent. The arrival of more than half a million Rohingya Muslims from Buddhist-dominated Myanmar since August 25 has put an huge strain on camps in Bangladesh where there are growing fears of a disease epidemic.
On Sep 15, the chargé d'affaires of the Myanmar Embassy in Dhaka, Aung Myint, was summoned by the foreign ministry, when a protest note was handed over to him. "We don't want to take actions that exacerbate their suffering".