The UN Office of the High Commissioner for Human Rights (OHCHR) on Wednesday said Myanmar had refused access to a UN Special Rapporteur tasked with assessing the human rights situation in the country.
There have been widespread claims of persecution against the mostly Muslim minority Rohingya community, hundreds of thousands of whom migrated to neighbouring Bangladesh fleeing sectarian violence associated with a crackdown against Rohingya rebels by Myanmar's security forces.
"The government of Myanmar has informed UN Special Rapporteur Yanghee Lee that all access to the country has been denied and cooperation withdrawn for the duration of her tenure," the OHCHR said in a statement.
Lee was scheduled to visit Myanmar in January to assess the human rights situation in the country, including the alleged abuses against the Rohingyas in western Rakhine state, Efe news reported.
Lee said the Myanmar government's attitude and lack of cooperation was "a strong indication that there must be something terribly awful happening in Rakhine as well as in the rest of the country".
Non-profit Doctors Without Borders last week estimated that at least 6,700 Rohingyas, including 730 children under five, were killed during the first 30 days of the crisis that began on August 25.
A special rapporteur appointed by the UN to a specific country is required to make at least two visits a year in order to prepare a complete report for the Human Rights Council and the UN General Assembly.
Since her appointment in 2014, Lee has visited Myanmar six times, although she was not always granted unfettered access by the country's authorities, who at the time cited security concerns.
The Myanmar government went one step further on Wednesday by completely blocking Lee's trip.
"It is a shame that Myanmar has decided to take this route.
They have said that they have nothing to hide, but their lack of cooperation with my mandate and the fact-finding mission suggests otherwise," Lee said, while still hoping that the authorities might reverse their decision.