operations were, in practice, "a mechanism to commit mass atrocities", the report said. "State security forces opened fire on Rohingya civilians from the land and sky. Soldiers and knife-wielding civilians hacked to death and slit the throats of Rohingya men, women, and children," it said.
"Rohingya civilians were burned alive. Soldiers raped and gang-raped Rohingya women and girls and arbitrarily arrested men and boys en masse."
The report said investigators from Fortify Rights and the Holocaust Museum’s Simon-Skjodt Centre for the Prevention of Genocide traveled to Rakhine and the Bangladesh-Myanmar border area, where Rohingya have fled. It quoted eyewitness testimony of mass killings in three villages in late August.
"When the killing was complete, soldiers moved bodies into piles and set them alight," after soldiers reportedly murdered hundreds in one attack, the report said, adding to chilling and consistent accounts of widespread murder, rape and arson at the hands of security forces and Buddhist mobs.
Human Rights Watch, for its part, interviewed 29 rape survivors. In every case but one, they were gang raped by two or more perpetrators. In eight cases, women and girls reported being raped by five or more soldiers.
Women described witnessing the murders of their young children, spouses, and parents before being raped. Many rape survivors said they endured days of agony walking with swollen and torn genitals to reach Bangladesh.
Human Rights Watch documented six cases of mass rape during which soldiers gathered women in groups before beating and gang-raping them. The report quoted 33-year-old Mamtaz Yunis as saying soldiers trapped her and about 20 other women on the side of a hill after they fled their village and raped women in front of them.
Global outrage is building over the violence, while Myanmar’s army insists it has only targeted Rohingya rebels. The watchdogs’ report came a day after Washington’s top diplomat, Secretary of State Rex Tillerson, said there were "credible reports of widespread atrocities committed by Myanmar’s security forces and vigilantes." Speaking during a visit to Myanmar, he urged authorities there to accept an independent investigation into those allegations.
The army and administration of de facto civilian leader Aung San Suu Kyi -- a Nobel peace laureate -- have dismissed reports of atrocities and refused to grant entry to UN investigators tasked with probing allegations of ethnic cleansing. "Without urgent action, a risk of further outbreaks of mass atrocities exists in Rakhine state and possibly elsewhere in Myanmar," Fortify Rights and the Holocaust Museum wrote.