The United States says action must be taken against Myanmar's military leaders whose operations have forced 500,000 Rohingya, a majority-Muslim ethnic group, to flee into Bangladesh.

Nikki Haley, the US ambassador to the United Nations, accused Myanmar's authorities on Thursday of carrying out "a brutal, sustained campaign to cleanse the country of an ethnic minority".

"The time for well-meaning, diplomatic words in this council has passed," she told the UN Security Council, which held its first public meeting on Myanmar since 2009, though it failed to arrive at a resolution.

Haley's comments came as more than 50 Rohingya refugees were missing on Friday after their boat capsized in driving wind, rain, and high seas.

The UN's International Organisation for Migration said about 130 people were believed to have been on board. Bangladesh police said there were 27 survivors, 19 dead, and more than 50 missing.

READ MORE: UN chief calls for urgent end to 'Rohingya nightmare'

Using the country's former name, Burma, Haley said, "We must now consider action against Burmese security forces who are implicated in abuses and stoking hatred among their fellow citizens."

It was the first time the United States had called for punishment of Myanmar's military leaders, but she stopped short of threatening to re-impose US sanctions that were suspended under the Obama administration.

Buddhist-majority Myanmar rejects accusations of ethnic cleansing and crimes against humanity and has denounced human rights abuses.

Its military launched a sweeping military offensive in response to coordinated attacks on the security forces by Rohingya rebels in Rakhine state on August 25.



Haley said Myanmar's military must immediately remove and prosecute those accused of abuses. She said it also must allow unhindered humanitarian access for UN agencies and other relief organisations, and "commit to welcoming all who have been displaced to return to their original homes".

In what appeared to be a rebuke to the country's Nobel Peace Prize-winning leader Aung San Suu Kyi, Haley said of the Rohingya crisis, "it should shame senior Burmese leaders who have sacrificed so much for an open, democratic Burma".

Myanmar, however, received strong support from close ally China as well as Russia.

"The international community must be aware of the difficulties faced by the Burmese government, be patient and provide its assistance," Chinese envoy Wu Haitao said.

Russian ambassador Vassily Nebenzia shifted the blame towards Rohingya fighters for "burning villages". "We must be very careful when we talk about ethnic cleansing and genocide," he said.

Nebenzia warned "excessive pressure" on Myanmar's government over the violence "could only aggravate the situation in the country and around it".

READ MORE: Scores of Rohingya feared drowned after boat capsizes

UN Secretary-General Antonio Guterres told the Security Council the violence had spiralled into the "world's fastest developing refugee emergency, a humanitarian and human rights nightmare".

He previously called the Rohingya crisis "ethnic cleansing" but did not repeat those words on Thursday. Instead, he referred to "a deeply disturbing pattern" of violence leading to "large movements of an ethnic group".

Myanmar's national security adviser said the crisis in Rakhine state "is due to terrorism and is not based on religion", and he urged the Security Council not to take measures that exacerbate the situation. "There is no ethnic cleansing and no genocide in Myanmar," U Thaung Tun said.

Diplomats accompanied by the media will visit northern Rakhine on Monday, U Thaung Tun said.