Top military leaders in Myanmar, including the commander-in-chief, must be investigated and prosecuted for genocide in Rakhine state and crimes against humanity in other areas, according to a UN report released on Monday.

The report – based on hundreds of interviews, research and analysis by a UN-mandated fact-finding mission — is the strongest condemnation by the UN of the Myanmar military’s actions following the crackdown on Rohingya Muslims last August.

It extended culpability for the humanitarian crisis in Rakhine state to Myanmar’s civilian government, led by Nobel Peace Prize laureate Aung San Suu Kyi. The civilian government, the report said, failed to speak out against unfolding events, spread “false narratives, oversaw the destruction of evidence in Rakhine state and blocked independent investigations”.

“Through their acts and omissions, the civilian authorities contributed to the commission of atrocity crimes,” it said. The UN report called for the case to be referred to the International Criminal Court of Justice, according to the BBC.

The Army’s tactics were “consistently and grossly disproportionate to actual security threats”, it said.

The fact-finding mission went beyond the military’s actions in Rakhine and investigated its conduct more broadly since 2011, a time when the world was celebrating the country’s opening to the West and nominally democratic transformation.

The UN report found “patterns of gross human rights violations and abuses committed in Kachin, Rakhine and Shan state” that “undoubtedly amount to the gravest crimes under international law”.

The Myanmar government has consistently said its operations targeted militant or insurgent threats. But the report said that the crimes it documented were “shocking for the level of denial, normalcy and impunity that was attached to them”.

“Military necessity would never justify killing indiscriminately, gang raping women, assaulting children and burning entire villages.”

The fact-finding mission concluded that there was “sufficient information” to open a genocide and war crimes investigation of senior Myanmar generals. A spokesman for Myanmar’s armed forces could not be reached for comment.

The report also noted that Myanmar authorities “do not tolerate scrutiny or criticism and use various laws to arrest, detain or harass human rights defenders and journalists”.

“The report will have a big impact internationally,” Richard Horsey, a former UN diplomat in Myanmar and long time Yangon-based analyst, was cited as saying by the Washington Post.

“Its specific finding that there was sufficient ground for investigation and prosecution of military commanders for genocide was likely to have particularly serious diplomatic, not only legal, consequences,” he said.

The UN fact-finding mission will present a detailed report to the Human Rights Council on September 18.