UN envoy Yanghee Lee is presently in Myanmar's Rakhine state to investigate the alleged persecution of Rohingya Muslims who have been reportedly facing state-sanctioned killings and human rights abuses.
Lee has been in Myanmar for almost two weeks, and was scheduled to visit camps for the internally displaced persons on Sunday. But the government denied her access, citing safety concerns.
The northwestern Rakhine state of the country, formerly known as Burma, is located along the border of Bangladesh and is home to most of the country's one million Rohingya Muslims.
As many as 500,000 Rohingyas have fled to Bangladesh after decades of persecution in Myanmar.
The United Nations says about 65,000 more people have moved to Bangladesh since attacks that killed nine Myanmar border police on October 9, sparking a heavy-handed security response.
Residents and refugees say Myanmar troops and police have carried out beatings, sexual assaults and extrajudicial killings, arbitrarily arrested villagers and set fire to homes.
Myanmar has denied almost all the allegations.