The United Nations investigator of human rights abuses in Myanmar expressed deep disappointment Thursday at what she described as an indifferent response by the country’s Nobel laureate leader to the violence raging against the Rohingya Muslim minority.

The comments by the investigator, Yanghee Lee of South Korea, a leading child rights expert appointed to her United Nations human rights post in 2014, underscored international frustrations over the behavior of the Myanmar leader, Daw Aung San Suu Kyi, regarding the persecution of the Rohingya.

Ms. Aung San Suu Kyi, a hero of democratic rights who endured years of house arrest by Myanmar’s military to become the top civilian politician of her country and de facto head of the government, has not criticized the deadly campaign against the Rohingya, who are widely reviled among the country’s Buddhist majority.

The campaign, carried out by Myanmar’s armed forces and allied militias, has uprooted hundreds of thousands of Rohingya from their villages in the western border state of Rakhine since August. The fallout has created a refugee and public health crisis in Myanmar’s impoverished neighbor, Bangladesh, as more than 600,000 people have fled across the border.