Half a million Rohingyas have crushed into camps in Bangladesh in just over a month, fleeing a Myanmar army campaign and communal violence that the U.N. describes as "ethnic cleansing."

They have come on foot or crossed the Naf River that bisects the two countries in overcrowded boats. One of them capsized in rough waters on Thursday agonizingly close to the shore. The bodies of 23 people have been retrieved from the water so far, but the death toll is expected to surge to around 60.

"Forty are missing and presumed drowned," International Organization for Migration (IOM) spokesman Joel Millman told reporters in Geneva.

In distressing scenes, refugees on Friday held funerals for loved ones, including children, who had left to seek sanctuary from violence that has cut through their homeland in Rakhine state.A woman carried a small white bundle to a grave for a Muslim burial, while male relatives wept at a school building where bodies had been laid out.

"My wife and two boys survived, but I lost my three daughters," Shona Miah, 32, told Agence France-Presse (AFP).

Those who have made it to Bangladesh have been squeezed into a vast makeshift refugee settlement that has become one of the world's largest in a matter of weeks.

According to the medical staff, the camps are in imminent danger of disease outbreak, as relief groups are overwhelmed by the numbers of hungry and traumatized Rohingyas.

A dire shortage of clean water, toilets and sanitation is spreading disease and pushing the camps to the precipice of a health disaster, the Red Cross warned.

"Our mobile clinics are treating more people, especially children, who are very sick from diarrheal diseases, which are a direct result of the terrible sanitation conditions," Bangladesh Red Crescent Society Secretary-General Mozharul Huq said.

In some of the camps, hundreds of refugees share a single toilet, said Martin Faller of the International Federation of Red Cross and Red Crescent Societies (IFRC). "The conditions for an outbreak of disease are all present; we have to act now, and we have to act at scale," he added.

The U.N. High Commissioner for Refugees (UNHCR) says nearly one in five arrivals are suffering from acute malnutrition.

Worsening conditions are compelling Rohingyas to try to move out of the wedge of land Bangladesh has set aside for the new arrivals.

But Bangladeshi police have stopped more than 20,000 Rohingyas from going inland, a senior official said Friday, after authorities imposed travel restrictions on the refugees fearing they will move further into the country.

Although Bangladesh has taken in the refugees, it has urged Myanmar to allow a safe return for them.

Myanmar says it is ready to begin repatriating refugees to a camp in the Maungdaw district of northern Rakhine.

But rights groups say the criteria for return is convoluted, discriminatory and carefully crafted to take back as few of the reviled minority as possible, as many Rohingyas do not possess the requisite documents to be allowed back or are unwilling to return to villages that have been burnt to the ground.

The Muslim minority is loathed in Myanmar where they are denied citizenship and are instead branded "Bengalis" or illegal migrants who do not belong in the Buddhist-majority country.

Attacks on police posts in Rakhine state by a Rohingya militant group on Aug. 25, set the crisis in motion.

The kickback by Myanmar's army killed hundreds and left scores of Rohingya villages in ashes.

Rohingyas who fled saying they survived slaughter by soldiers and ethnic Rakhine Buddhists who were once their neighbors.

Ethnic Rakhines and Hindus have also been displaced inside Rakhine state, accusing Rohingya militants of atrocities.

Rohingyas are still on the move, and the U.N. Secretary-General Antonio Guterres has warned that the systemic violence could spill further south to the central part of Rakhine state, threatening a further 250,000 Muslims with displacement. On Thursday, as the U.N. Security Council held its first meeting on Myanmar in eight years, he implored Myanmar's leaders to end the "nightmare" faced by refugees.

But the council failed to agree on a joint resolution after China and Russia supported Myanmar's right to defend itself.

International pressure has so far done little to rein in Myanmar army operations.

Access to the violence-stricken part of Rakhine is tightly controlled by the military, preventing international aid groups reaching desperate Rohingyas left behind or independent reporting on the crisis.