On arrival, they will go to Cox’s Bazar where half a million Rohingyas from neighbour Myanmar's Rakhine State took shelter fleeing ethnic cleansing.
This is the largest displacement and mass refugee movement in the region in decades.
The UN office in Dhaka said the purpose of the joint mission is to see, first-hand, the devastating humanitarian situation of the Rohingya refugees.
The original response plan, launched on Sep 7, sought $77 million to assist 300,000 people.
As of 29 September, the program has received $36.4 million, or 47 percent, of the funding requirements for the coordinated response.
Humanitarian partners are now revising the initial plan to account for the huge additional needs, the UN office said.
They will leave Dhaka on Sep 4.