COX'S BAZAR (Bangladesh) • UN chief Antonio Guterres exhorted Myanmar's leaders to end the "nightmare" faced by Rohingya refugees fleeing an army campaign, even as more than 60 people were feared to have drowned when a boat carrying Rohingya families capsized off Bangladesh.

More than half a million Rohingya Muslims have poured into Bangladesh in the last month, fleeing a Myanmar military crackdown on Rohingya rebels that has gutted villages across the northern Rakhine state.

Scores have drowned while trying to cross waters separating the two countries, while those who survive face new dangers as they cram into squalid refugee settlements where food and clean water are in short supply.

The growing humanitarian crisis prompted the United Nations Security Council to hold its first meeting on Myanmar in eight years, though it failed to arrive at a joint resolution.

The United States slammed the Myanmar army for trying "to cleanse the country of an ethnic minority", while China and Russia offered support to the Myanmar authorities, who have vehemently rejected allegations that ethnic cleansing is under way.

Speaking to the 15-member council, Mr Guterres urged Myanmar to halt military operations and open humanitarian access to the region. "The situation has spiralled into the world's fastest-developing refugee emergency, a humanitarian and human rights nightmare," he said, while calling for those displaced by the conflict to be allowed to go home.

He noted that the "systemic violence" could cause unrest to spill south to the central part of Rakhine state, threatening 250,000 Muslims with displacement.

Some of the strongest criticism came from US envoy to the UN Nikki Haley, who accused the Myanmar authorities of waging a "brutal, sustained campaign to cleanse the country of an ethnic minority".

She urged countries to suspend providing weapons to Myanmar over violence against Rohingya Muslims. It was the first time the US had called for punishment of Myanmar's military leaders behind the repression, but she stopped short of threatening to reimpose US sanctions which were suspended under the Obama administration.

Fires have razed hundreds of communities in northern Rakhine over the past month, in what rights groups say is an army-led effort to drive out the stateless minority that has faced decades of persecution.

Myanmar, a mainly Buddhist country, has denied the allegation, and defended its operations as a proportionate crackdown on the Rohingya militants whose deadly raids on police posts on Aug 25 sparked the military backlash.

The authorities have restricted access to the epicentre of the violence but agreed this week to allow a UN visit to the conflict zone. The trip was postponed to Monday due to bad weather, state media reported.

The drowning tragedy is the latest in a series of deadly accidents as desperate refugees surge into Bangladesh, where they are penned into ramshackle tent cities amid dire shortages of aid. Witnesses and survivors said the vessel that overturned on Thursday was just metres from the coast in rough waters, after it was lashed by torrential rain and high winds.

An official with the International Organisation for Migration said yesterday that 23 people were confirmed dead and 40 were missing. Seventeen survived. "We are now saying 40 missing, which suggests the total fatality rate will be in the range of 63," the official, Mr Joe Millman, told reporters in Geneva.

Earlier, Bangladesh Coast Guard commander Nasir Uddin said the bodies of 16 people - mostly children - were found after the boat capsized on Thursday. Three more bodies were retrieved yesterday.

AGENCE FRANCE-PRESSE, REUTERS