(CNN) A senior United Nations official investigating Myanmar's ongoing crackdown against the Rohingya says she is increasingly convinced it may amount to genocide.
More than 680,000 Rohingya Muslim refugees have fled Buddhist-majority Myanmar to neighboring Bangladesh since August 2017, bringing with them stories of mass murder and destruction at the hands of the country's military.
"I am becoming more convinced that the crimes committed following 9 October 2016 and 25 August 2017 bear the hallmarks of genocide and call in the strongest terms for accountability," said Yanghee Lee, the Special Rapporteur on human rights in Myanmar.
Lee, who was speaking to the UN's Human Rights Council in Geneva on Monday, also called for a body to be set up at Cox's Bazar in Bangladesh, where most Rohingya have sought refuge, to compile evidence of human rights abuses in Myanmar.
She said its "aim would be to facilitate impartial, fair and independent international criminal proceedings in national or international courts or tribunals."
CNN contacted Myanmar's government for comment but didn't receive an immediate response.
Lee was speaking as her scathing report on the state of human rights in Myanmar was released, in which she calls for calls "for a thorough, impartial and credible investigation to be conducted without delay and perpetrators to be held responsible for the alleged crimes that were committed in Rakhine State".
Myanmar denies all charges, saying its military has only targeted suspected terrorists that killed 12 security officials in late August. However, in January the military admitted involvement in the killing of 10 Rohingya buried in a mass grave.
The UN and the US say they believe the violence constitutes ethnic cleansing. In December last year Zeid Ra'ad Al Hussein, the UN's High Commissioner for Human Rights, also suggested that genocide may have been committed against the Rohingya.
The UN has a detailed definition of genocide, which it describes as acts committed with an "intent to destroy, in whole or in part, a national, ethnic, racial or religious group".
Under an agreement signed by Yangon and Dhaka in November, Rohingya refugees will be sent back to Myanmar, where they say their lives are under threat. The date of their return has yet to be agreed and rights groups have said the move is dangerously premature.
Lee, who was banned from Myanmar last year after Yangon claimed a previous report by her was biased and unfair, said she had seen evidence that Myanmar's military was continuing to target Rohingya, razing their villages.
"There is an increasing amount of credible evidence, including satellite images, which indicates that whole villages that were once home to Rohingya have been bulldozed to the ground," she said.
"This casts further doubt on the sincerity of Myanmar regarding repatriating the Rohingya from Bangladesh," she added.
Amnesty International on Monday published a report containing satellite images that it said showed Rakhine State, home to the majority of Rohingya, being militarized at an alarming pace.
The report said Myanmar authorities are building security force bases and bulldozing land where Rohingya villages were destroyed.
"What we are seeing in Rakhine State is a land grab by the military on a dramatic scale. New bases are being erected to house the very same security forces that have committed crimes against humanity against Rohingya," said Tirana Hassan, Amnesty International's Crisis Response Director.
"This makes the voluntary, safe and dignified return of Rohingya refugees an even more distant prospect. Not only are their homes gone, but the new construction is entrenching the already dehumanizing discrimination they have faced in Myanmar."