Myanmar's security forces are alleged to have committed widespread human rights abuses against Rohingya Muslims in recent months.
Escalating violence and allegations of widespread human rights abuses against Rohingya Muslims have put Myanmar's international reputation at stake, the United Nations has warned.
The conflict in Myanmar's Rakhine State has sent hundreds of Rohingya fleeing across the border to Bangladesh amid allegations that the security forces are acting with impunity against the Muslim minority.
The crisis poses a serious challenge to the government of Aung San Suu Kyi, who swept to power last year on promises of national reconciliation. On Monday, she was forced to postpone a visit to Indonesia after protests there over her country's bloody crackdown.
In a statement, Adama Dieng, the UN's special adviser on the prevention of genocide, said the allegations "must be verified as a matter of urgency" and called on the government to allow access to the area.
Crackdown on Rohingya Muslims in Myanmar continues. UN official warns of ethnic cleansing. pic.twitter.com/W1w5dgWgPC— TRT World (@trtworld) November 25, 2016
"If they are true, the lives of thousands of people are at risk. The reputation of Myanmar, its new government and its military forces is also at stake in this matter," he said.
"Myanmar needs to demonstrate its commitment to the rule of law and to the human rights of all its populations. It cannot expect that such serious allegations are ignored or go unscrutinised," he said.
Soldiers have poured into the area along Myanmar's frontier with Bangladesh, responding to coordinated attacks on three border posts on October 9 that killed nine police officers. The army says it is targeting those behind the attack.
Myanmar's military and the government have rejected allegations by residents and rights groups that soldiers have raped Rohingya women, burnt houses and killed civilians during the military operation in Rakhine.
The violence, the most serious bloodshed in Rakhine since hundreds were killed in communal clashes in 2012, has renewed international criticism that Suu Kyi has done too little to alleviate the plight of the Rohingya minority, who are denied citizenship and access to basic services.
"The government needs, for once and for all, to find a sustainable solution to the situation of the Rohingya Muslims and other religious and ethnic minorities in Myanmar, a solution that is in full compliance with the international human rights standards that the government has pledged to respect," Dieng said.