Published: 2017-09-13 22:42:45 BdST
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.
A helicopter hovers over the burning villages at Maungdaw in Rakhine State. The scene was captured by the photographer from Shah Porir Dwip in Teknaf. Photo: mostafigur rahman
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.
Suu Kyi cancelled a trip to the upcoming UN General Assembly to deal with the crisis, her office said on Wednesday.
Villages in Maungdaw area in Rakhine State are set on fire allegedly by the Myanmar Army and other forces. The photo is taken from Shah Parir Dwip in Teknaf. Photo: mostafigur rahman
The government of Myanmar, also known as Burma, says its security forces are fighting Rohingya militants behind a surge of violence in Rakhine state that began on Aug. 25, and they are doing all they can to avoid harming civilians.
The government says about 400 people have been killed in the fighting, the latest in the western state.
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."