YANGON — Hundreds of thousands of Rohingya Muslims who remain inside Myanmar face systematic persecution and are living under the threat of genocide, a U.N. fact-finding mission said on Monday, repeating calls for top generals to face trial.

Myanmar security forces are accused of killings, gang rape and arson during a crackdown that drove more than 730,000 people to flee western Rakhine state for neighboring Bangladesh after attacks on police posts by Rohingya insurgents in August 2017.

Myanmar has rejected most of the accusations and dismissed a report last September by a U.N-appointed panel which said military officers carried out the campaign against the Rohingya with "genocidal intent" and should stand trial.

"The threat of genocide is continuing for the remaining Rohingya," Australian human rights lawyer and panel member Christopher Sidoti said in a statement accompanying a new report, adding that Myanmar was failing to prevent and punish genocide.

Some 600,000 Rohingya are living in "deplorable" conditions in Myanmar’s Rakhine state, subject to restrictions on movement that touch almost every aspect of their lives, the U.N report said.

"These facts underscore the impossibility of return for the nearly one million Rohingya refugees, mostly in Bangladesh," it added.

Myanmar rejected the fact-finding mission when it was formed at the Human Rights Council in Geneva in March 2017, with a mandate to investigate military abuses against the Rohingya and in other conflicts with ethnic armed groups in Myanmar.

The new report accuses the security forces of "torture and ill-treatment" of suspected insurgents in northern Myanmar, and says sexual and gender-based violence by the Myanmar military "remains a prominent feature of conflicts in Shan and Kachin states".

Government spokesman Zaw Htay did not answer a telephone call to seek comment.

Two military spokesmen did not answer phone calls seeking comment.

The U.N panel said the evidence it gathered from nearly 1,300 interviews with witnesses had been passed to a new investigative mechanism for Myanmar which will support any future prosecution in international courts.

"The scandal of international inaction has to end," Sidoti said, "Unless the United Nations and the international community take effective action this time, this sad history is destined to be repeated."