UN Secretary-General Antonio Guterres yesterday called on authorities in Myanmar to end violence against Rohingyas and acknowledged the situation there is best described as ethnic cleansing.

The humanitarian situation in Myanmar was "catastrophic," Guterres said, and called on all countries to do what they could to supply aid.

"I call on the Myanmar authorities to suspend military action, end the violence, uphold the rule of law and recognise the right of return of all those who had to leave the country," Guterres said at a news conference.

Pressure has been mounting on Myanmar to end violence that has sent about 370,000 Rohingya Muslims fleeing to Bangladesh, with the United States calling for protection of civilians and Bangladesh urging safe zones to enable refugees to go home.

Asked if the situation could be described as ethnic cleansing, Guterres replied: "Well I would answer your question with another question: When one-third of the Rohingya population had to flee the country, could you find a better word to describe it?"

The secretary-general also said he has spoken to Aung San Suu Kyi, Myanmar's national leader, several times.

"This is a dramatic tragedy. People are dying and suffering at horrible numbers and we need to stop it. That is my main concern," he said.

The UN's top human rights official earlier this week denounced Myanmar for conducting a "cruel military operation" against the Rohingya, branding it "a textbook example of ethnic cleansing."