In a fresh report, Thomas Andrews, the UN Special Rapporteur on the rights situation in Myanmar, called for the international community to "act urgently and decisively" to support those demanding a return to democracy in the country.

"The stakes could not be higher," he said.

The UN Security Council, he said, should urgently "impose a global arms embargo" and "impose targeted economic sanctions against the Myanmar military and its sources of revenue."

It should also refer the situation in the country to the International Criminal Court "to investigate and possibly prosecute atrocity crimes that have occurred, including genocide, war crimes, and crimes against humanity," the report said.

The UN and the international community must meanwhile deny the military junta recognitions as the country's legitimate government, the expert said.

"I urge the members of the (Security) Council to consider the unrelenting brutality that we are witnessing in Myanmar," he said in a statement.

Myanmar has been in uproar since the military seized power on February 1, ending a decade-long experiment with democracy and triggering a mass uprising that the junta has increasingly sought to quash with lethal force.

Wednesday marked the bloodiest day so far, with the UN saying at least 38 people died, as online images streamed out of Myanmar showing security forces firing into crowds and blood-covered bodies with bullet wounds in their heads.

The UN Security Council is due to discuss the crisis on Friday, as international pressure mounts.

Western powers have repeatedly hit the generals with sanctions, and 41 states have imposed arms embargos on Myanmar.

- 'Terrified' -

Andrews' report covered the period up to March 1, so did not include the escalating violence in recent days.

But he had already said on February 17 that he was "terrified" at developments in the country, warning "we could be on the precipice of the military committing even greater crimes against the people of Myanmar."

The US national said in his report that he had requested access to Myanmar as soon as he was named to his post last year, back when Aung San Suu Kyi was still in charge of the civilian government.

But his request had been denied with reference to the pandemic.

Andrews meanwhile said it was clear that "the people of Myanmar are experiencing the illegal overthrow of their government and the brutal repression of a military authoritarian regime."

He hailed that they had "risen up in opposition as a diverse yet powerfully unified whole."

"The non-violent civil disobedience movement is proving to be remarkably effective, drawing its organic power from the unflinching and democratic desires of the people," he said.

"Indeed, Myanmar appears to have never been more unified."

He called on the international community to "rise to the occasion of this moment in history by following the lead and the inspiration of the people of Myanmar," voicing hope that "justice, dignity, and human rights will prevail."