A senior official from the UN's World Food Program (WFP) told AFP they were now prepared to provide massive food and other emergency aid if the influx continues in coming weeks.
"All the UN agencies together have now set a plan for a new influx of 700,000. We can cover if the new influx reaches 700,000," said the WFP's deputy chief in Bangladesh, Dipayan Bhattacharyya, today.
Rohingya have been fleeing Rakhine state in northeast Myanmar for decades. The new influx began on August 25 when deadly attacks by Rohingya militants on Myanmar police posts prompted a huge crackdown by the military.
Bhattacharyya said the hunger situation in camps has improved as food aid from WFP and other agencies is now reaching the refugees.
He said the plan also covers some 300,000 Rohingya who were already sheltering in southeast Bangladesh before the latest influx began -- meaning it could cater for a million people in total.
"No one would be left out from any humanitarian assistance," he said, adding that the WFP would need about $80 million for the massive aid.
Grandi said there had been an "incredible outpouring of local generosity" but that now needed to be "beefed up by massive international assistance, financial and material".
A United Nations official last week said it would need USD 200 million over the next six months to handle the Rohingya crisis.
The UN made an emergency appeal for $78 million on September 9, but UN resident coordinator in Bangladesh Robert Watkins said much more would be needed as the exodus grows.
Impoverished Bangladesh, which earned praise for opening up its border, has eased restrictions on aid groups working in refugee camps and sought USD 250 million from the World Bank to fund emergency relief.