In a report released on Sunday, the UN-led Inter-Sector Coordination Group (ISCG) said an estimated 603,000 refugees from Rakhine had crossed the border into Bangladesh since August 25.
"Cross border movement of over 14,000 newly arrived refugees has been verified in the past week," said the ISCG, which is directing the humanitarian effort in the region.
The report came as authorities in Bangladesh have been bracing for another possible surge in Rohingya refugee arrivals.
Commander of Border Guards Bangladesh Lieutenant Colonel S.M. Ariful Islam told AFP that Rohingya refugees had received videos from families across the border showing displaced Muslims massing near crossing points, while waiting for an opportunity to cross.
"We have seen some videos sent by people across the border. There are many gathered there. The number could be big," the Bangladeshi official said.
Last week, about 10,000 refugees were left stranded in no-man's-land near Anjumanpara village for three days after being prevented from crossing into Bangladesh.
Iqbal Ahmed, a spokesman for Border Guards Bangladesh, confirmed that an estimated 10,000-15,000 refugees were heading to Anjumanpara, adding, "We heard from their relatives that the Myanmar army has stopped them from heading to the border."
In recent days, hundreds of refugees have crossed the Naf River dividing the two countries.
"Those that came told us thousands were still stranded on the other side of Naf," Jashim Uddin, a volunteer for the International Organisation for Migration, said.
Refugees arriving on Sunday described violence in their villages in Rakhine and food shortages.
"We hardly had any food for the last 10-15 days. They torched our home. We did not have any choice but to leave," said a Rohingya refugee from Myanmar’s coastal village of Shah Porir Dwip.
Authorities are on high alert for fishermen seeking to ferry refugees to Bangladesh via the open sea.
"It is risky, but you can make a lot of money ferrying Rohingya to Bangladesh," said local fisherman, Shawkat Hossain.
Buddhists hold anti-Rohingya protest
On Sunday, hundreds of hard-line Buddhists held a protest rally to urge Myanmar's government not to repatriate the Rohingya Muslims who have fled to Bangladesh. The protest took place in Sittwe, the capital city of Myanmar's Rakhine state.
Protesters, including some Buddhist monks, demanded that the government not take back the refugees.
Aung Htay, a protest organizer, said, "But if these people don't have the right to be citizens ... the government's plan for a conflict-free zone will never be implemented,"
Under pressure from the international community, the government of Myanmar's de facto leader, Aung San Suu Kyi, recently said it was willing to take back Rohingya refugees who fled to Bangladesh.
The Rohingya have been fleeing Myanmar amid persecution at the hands of extremist Buddhists and the military. Since October 2016, Myanmar’s army has been carrying out a military crackdown in Rakhine, where a large number of the Rohingya live.