The Myanmar government has not sent any investigators to the squalid Rohingya refugee camps in Bangladesh, which now constitute the world’s largest mega-settlement of displaced people. With monsoon rains coming, aid groups worry that large sections of these settlements could wash away.

Myanmar officials have rejected outright fact-finding reports that were submitted on Monday to the United Nations Human Rights Council that documented severe violations of the rights of ethnic minorities in Myanmar, including the Rohingya.

Speaking to the council, Yanghee Lee, the United Nations special rapporteur on human rights in Myanmar, said the military’s campaign against the Rohingya bore “the hallmarks of genocide” and urged international legal action against “the individuals who gave the orders and carried out violations against individuals and entire ethnic and religious groups.”

On Monday, Amnesty International accused the Myanmar government of destroying the remains of Rohingya villages in a campaign dedicated to “erasing evidence of crimes against humanity.” Using satellite imagery, Amnesty documented how new security bases were being built on land that had once housed Rohingya communities. Separately, rights groups have documented more than 300 Rohingya villages in northern Rakhine that were razed by fire since last August.

The Myanmar government says that any recent bulldozing has been for benign purposes.

“We are clearing the land to make it suitable for rebuilding for the refugees,” Mr. Aung Tun Thet said on Wednesday at a news conference in Naypyidaw, the Myanmar capital.

Both the Bangladesh and Myanmar governments have talked up voluntary repatriations as a solution to one of the world’s most urgent refugee crises. So far, only 8,032 of the hundreds of thousands of Rohingya now crowded into the Bangladesh camps have said they are willing to be repatriated, according to a list drawn up by the Bangladeshi authorities last month.

On Wednesday, U Myint Thu, Myanmar’s permanent secretary for foreign affairs, said that Bangladesh’s repatriation list was missing “essential information” needed to verify that those people had indeed fled from Myanmar. Consequently, only 374 of the 8,032 applicants had been verified and approved by his government, he said.