New Delhi: The United Nations has said that situation in Myanmar is a "textbook example of ethnic cleansing" as the number of Rohingya Muslims fleeing Myanmar for Bangladesh topped 300,000.

The UN warning came as it emerged the Dalai Lama had written to Aung San Suu Kyi urging Myanmar's de facto civilian leader to find a peaceful solution to the crisis in the mainly Buddhist country. 

"Questions that are put to me suggest that many people have difficulty reconciling what appears to be happening to Muslims there with Myanmar's reputation as a Buddhist country," the Tibetan spiritual leader wrote in a letter to Suu Kyi shortly after the latest fighting broke out.

Since the latest upsurge in violence on August 25, hundreds of thousands have flooded across the border into Bangladesh bringing stories of entire villages burned to the ground by Buddhist mobs and Myanmar troops.

On Monday the UN human rights chief Zeid Ra'ad Al Hussein accused Myanmar of waging a "systematic attack" on the Rohingya and warned that "ethnic cleansing" seemed to be under way.

"Because Myanmar has refused access to human rights investigators the current situation cannot yet be fully assessed, but the situation seems a textbook example of ethnic cleansing," he told the UN Human Rights Council.

Refugee camps and makeshift settlements near the border with Myanmar, which already hosted hundreds of thousands of Rohingya before the latest upsurge in violence, are now completely overwhelmed.

That has left tens of thousands of new arrivals with nowhere to shelter from the monsoon rains. Most have walked for days and the United Nations says many are sick, exhausted and in desperate need of shelter, food and water.