The United Nations says the number of Rohingya Muslims that have fled from Myanmar to Bangladesh since August has now topped 500,000.

U.N. deputy spokesman Farhan Haq tells reporters "it is the largest mass refugee movement in the region in decades."

Haq says with the latest figure from the U.N. humanitarian office, "the total number of Rohingya refugees in Bangladesh is believed to be well over 700,000 people."

Haq adds that aid agencies are working with the government to improve road access to refugee camps and to facilitate humanitarian aid deliveries.

He says that as of Thursday, humanitarian partners have received just $36.4 million of the $77 million the U.N. called for in early September. Haq says the scale of the emergency has soared and the appeal will be increased.