Tomas Ojea Quintana, the United Nations' special rapporteur on human rights who returned during the weekend after visiting Myanmar, said the Southeast Asian nation, formerly called Burma, needs to tackle these challenges for the success of democratic transition and national reconciliation.
Myanmar, which until last year had been ruled for decades by a military junta, witnessed clashes in June in its western Rakhine state between the Buddhists and Rohingya, resulting in the deaths of dozens of people and displacement of thousands of others while raising concerns about the country's reform process.
Quintana highlighted a number of key human rights concerns, including the situation in Rakhine state and detention of U.N. staff members in connection with the Rakhine situation, the United Nations said in a release.
"The human rights situation in Rakhine state is serious," Quintana said in a statement at the end of his visit.
He called for an independent investigation into allegations of serious human rights violations, including alleged excessive use of force by security and police personnel.
"It is of fundamental importance to clearly establish what has happened in Rakhine state and to ensure accountability. Reconciliation will not be possible without this, and exaggerations and distortions will fill the vacuum to further fuel distrust and tensions between communities," he said.
Myanmar officials have denied using excessive force. The June violence erupted after the rape and killing of a Buddhist woman, spreading to other parts of the country.
Separately, Quintana welcomed the Myanmar government's cease-fire agreements with 10 ethnic armed groups, and their ongoing dialogue.