Since Aug. 25, about 520,000 Rohingya have crossed from Rakhine into Bangladesh, according to the UN.
The findings are contained in the first comprehensive report on the crisis in Myanmar's Rakhine State by the U.N. Human Rights Office, after interviews with dozens of people on the ground.
Renata Lok-Dessallien was the focus of a BBC investigation last month in which she was accused of suppressing internal discussion on Rohingya Muslims.
According to the United Nations researchers, measures against the minority group began nearly a month before the August 25 attacks on police posts by Muslim militants that served as a pretext for what Myanmar's military called "clearance operations" in Rakhine.
The violence has driven more than 500,000 Rohingya to neighboring Bangladesh since late August, where most live in refugee camps or out in the open.
UN High Commissioner for Human Rights Zeid Ra'ad al-Hussein - who has described the government operations as "a textbook example of ethnic cleansing" - said in a statement that the actions appeared to be "a cynical ploy to forcibly transfer large numbers of people without possibility of return".
The report said that teachers, cultural and religious leaders were targeted "in an effort to diminish Rohingya history, culture and knowledge".
Young girls were raped by men "all dressed in army uniforms" in front of their families, civilians shot at close range or in the back as they fled, and people burned alive, the report said. "If you do not leave, we will torch your houses and kill you", they said, according to the UN.
The UN has announced that it is on "full alert" for a mass exodus of Rohingya Muslims as reports show a sharp spike of them fleeing Myanmar, APA reports quoting Press TV.
The parliamentary body called upon the government to keep vigilance on different NGOs so that they can not lure religious minded and poor Rohingya refugees into involving militancy or any subversive activities.