THE thousands of Bangladeshi migrants and Rohingya people who are adrift at sea must be saved, the UN has told the leaders of the countries whose shores they seek.

Already, almost 1000 of the 88,000 attempting to cross the Bay of Bengal and the Andaman Sea since 2014 are believed to have died at sea. The same number were killed by mistreatment and privation at the hands of traffickers and abusive smugglers, the UN believes.

In a statement issued on Tuesday, several UN agencies called on the leaders of Indonesia, Malaysia, and Thailand to allow the migrants to disembark.

The UN High Commissioner for Human Rights, Prince Zeid Ra'ad Al-Hussein, said that he was "appalled" by reports that the countries had been pushing boats full of migrants back out to sea. About 6000 are believed to be still stranded at sea.

Prince Zeid said that the migration would continue until the government of Myanmar addressed "institutional discrimination" against the Rohingya.

Christian Solidarity Worldwide is among the 27 agencies that wrote to the UN secretary-general, Ban Ki-moon, on Wednesday, urging him to give his personal attention to the "escalating humanitarian crisis" in the western state of Rakhine, where the Rohingya live. At least 70 per cent of Rohingya currently have no access to safe water or sanitation.

Arrival on shore is no guarantee of safety for migrants. Thai authorities have unearthed mass graves with dozens of bodies, believed to be those of smuggled Rohingya and Bangladeshis. Recent arrivals told the UN that they were beaten with pipes and wires, hung upside-down from trees, and had fingernails pulled off with pliers.