As many as 100,000 more people may be waiting to cross into Cox's Bazar from North Rakhine's Buthidaung Township, IOM says quoting observers, report agencies.
An estimated 2,000 Rohingyas are still arriving in Cox's Bazar, Bangladesh a day, having fled violence in Myanmar's North Rakhine State, according to IOM staff monitoring the Bangladesh-Myanmar border.
The new arrivals bring the total number of Rohingyas to cross into Bangladesh since August 25 to an estimated 515,000, said the International Organization for Migration (IOM).
Meanwhile, Bangladesh Home Minister Asaduzzaman Khan confirmed Sunday his visit to Myanmar this month.
The Rohingya issue will dominate at the minister-level meeting to be held in Myanmar as Bangladesh expects the return of all Rohingyas living in Bangladesh to their homeland through diplomatic efforts.
"We believe we'll be able to help Rohingyas return to their homeland through diplomatic efforts," Asaduzzaman told reporters.
He said the Bangladesh envoy to Myanmar is also working to finalise the agenda of the meeting with his Myanmar counterpart.
"The key agenda will be Rohingya issue. We'll discuss the problem."
On September 14, the Bangladesh government allocated 2,000 acres of forest land to set up a new camp adjacent to the existing Kutapalong makeshift settlement.
It allocated another 1,000 acres of land to cope with the spiralling numbers.
The IOM said the challenges of establishing the camp on inaccessible, hilly terrain, are vast.
"The site is entirely undeveloped and will require planning and infrastructure investment for roads and bridges, the installation of drainage systems and soil protection earthworks to reduce the risk of landslides," said the IOM.
It is currently accessible by just one road - the Cox's Bazar-Teknaf Highway - which is already permanently congested by aid trucks and local traffic.
Many of the Rohingyas arrive in Teknaf - Cox's Bazar's southernmost upazila or sub-district - but then move north to Ukhiya sub-district and the vast, teeming makeshift settlements of Kutupalong, Balukhali and neighbouring satellite sites.
They arrive exhausted, hungry and usually with nothing more than the clothes on their back, having walked for days and then braved a dangerous river or sea crossing. Many show signs of malnutrition.
IOM, the UN Migration Agency, this week appealed to the international community for US$ 120 million through March to provide desperately needed aid to Rohingyas who have flooded into Cox's Bazar over the past six weeks.
It aims to target 450,000 individuals (90,000 households) over the next six months.
The IOM appeal is part of a broader humanitarian response plan seeking US$ 434 million to help 1.2 million people, including the Bangladeshi host community.
At the request of the government of Bangladesh, IOM is hosting the Inter Sector Coordination Group, which is coordinating the work of aid agencies responding to the humanitarian crisis triggered by the influx.
IOM's operations focus on six sectors: shelter and core relief items; site management; water, sanitation and hygiene (WASH); health; coordination; protection; and communication with communities.
Life-saving services delivered IOM and its partners include clean water and sanitation, shelter, food, security, health care, education, and psychological support for the most vulnerable individuals, many whom are suffering from acute mental trauma or are survivors of sexual violence.
To date, IOM has distributed some 40,000 plastic tarpaulins to provide basic shelter for the Rohingyas since 25 August.
These include some 4,000 shelter kits comprising two plastic sheets, two ropes, two blankets, and one sleeping mat per family, donated by the United Kingdom's Department for International Development (DFID).
