Myanmar's army has issued a report forcefully denying they committed atrocities against the Rohingya, the embattled ethnic minority who have fled in their hundreds of thousands across the border to Bangladesh.
More than 618,000 people have fled to the neighbouring Bangladesh after the army launched an offensive in the north of the western Rakhine State in response to the attacks by a group of Rohingya insurgents on security posts in late August.
US Secretary of State Rex Tillerson has called for a credible investigation into allegations of human rights abuses against Rohingya Muslims after a meeting with Myanmar's civilian and military leaders.
A senior US State Department official later said the top diplomat would press Myanmar's powerful army chief on Wednesday to halt the violence in Rakhine and make it safe for Rohingya to return.
More than 600,000 Rohingya have flooded into Bangladesh since late August, and now live in the squalor of the world's biggest refugee camp.
"The Burmese military's absurd effort to absolve itself of mass atrocities underscores why an independent global investigation is needed to establish the facts and identify those responsible", said Brad Adams, Asia director at Human Rights Watch.
Measures proposed in the report to the global community to put an end to the violence include "sanctions on the individuals responsible for crimes in Rakhine, instituting an arms embargo on Myanmar, and referring the situation to the worldwide Criminal Court".
The U.S. first imposed economic sanctions on Myanmar in 1990 in an attempt to weaken the then-military regime and its business affiliates.
"It is a worrying escalation in a protracted tragedy and a potential source of instability in the region, and radicalization", Guterres said, welcoming ASEAN efforts to provide humanitarian aid.
The conservative ASEAN, which includes Myanmar and other countries critical of its handling of the Rohingya crisis like Malaysia, has refused to formally discuss the crisis as a bloc in a strongly critical manner.
The Nobel peace prize victor has failed to speak out strongly over the Rohingya's plight.
"They're still coming, risking their lives, driven by fears of starvation and violence", Shariful Azam, a police official in Bangladesh's Cox's Bazar, a narrow spit of land where the world's most urgent humanitarian crisis is unfolding.
Canada's Justin Trudeau said he had spoken to Myanmar's de facto leader.
"After recording countless stories of horror and using satellite analysis to track the growing devastation we can only reach one conclusion: These attacks amount to crimes against humanity".
Representatives of the United Nations and the European Union have described the situation as "ethnic cleansing", an assessment echoed by British Prime Minister Theresa May this week.
The human rights group called for a United Nations fact-finding mission and requested other independent investigators be given full access to Rakhine State.