Myanmar's military carried out mass killings and gang rapes of Muslim Rohingya with "genocidal intent" and the commander-in-chief and five generals should be prosecuted for orchestrating the gravest crimes under law, U.N. investigators said Monday.

The civilian government led by Aung San Suu Kyi has allowed hate speech to thrive, destroyed documents and failed to protect minorities from crimes against humanity and war crimes by the army in Rakhine, Kachin and Shan states, they said in a report.

In doing so, it "contributed to the commission of atrocity crimes," the report said.