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Bangladeshi President Sheikh Hasina on Thursday accused Myanmar of failing to honor a verbal commitment to take back Rohingya Muslims who have fled a crackdown she described as tantamount to genocide.

Hasina's remarks at the annual gathering of world leaders at the United Nations came as the U.N. Human Rights Council agreed to set up a team to collect evidence of alleged crimes that one day could be used to prosecute suspected perpetrators.

U.N.-backed investigators have already said the reported atrocities could amount to genocide and other war crimes. Myanmar, which barred the investigators from the country, has rejected that reporting as "replete with unverified information."

"We are appalled by what we have seen in U.N. reports about atrocities against the Rohingya who have now taken shelter in Bangladesh, which are tantamount to genocide and crimes against humanity," Hasina told the General Assembly.

She appealed for more international support for the 1.1 million Rohingya refugees now sheltering in Bangladesh, and urged an "early, peaceful solution" to the crisis. Most have arrived since August 2017 when attacks by Rohingya militants on Myanmar security forces triggered a massive retaliation that prompted a massive cross-border exodus of civilians.

"Despite their verbal commitment to take back the Rohingya, in reality the Myanmar authorities are yet to accept them back," Hasina said.

International pressure is mounting on Myanmar, which is to address the General Assembly on Friday. The Organization of Islamic Cooperation on Thursday hosted a ministerial-level meeting on the sidelines of the assembly to address the plight of the Rohingya, following another hosted by Britain earlier in the week. Both were conducted behind closed doors.

Also, a U.S. government investigation released Monday concluded that the Myanmar military had targeted Rohingya civilians indiscriminately and often with "extreme brutality" in a coordinated campaign to drive the minority Muslims out of the country.

The report provided statistical analysis. It said most of those interviewed had witnessed a killing, and half had witnessed sexual violence, and the military was identified as the perpetrator in 84 percent of the killings or injuries they witnessed.

Human rights groups criticized the Trump administration for not describing the crackdown as "genocide." The U.S. has characterized the gross abuses as "ethnic cleansing," which is not a criminal definition.

Deputy Secretary of State John Sullivan told reporters Thursday that the investigation, based on interviews with more than 1,000 Rohingya refugees, was intended as a forensic description and not to make legal judgements.

But he added that the U.S. is working toward accountability for those responsible, and on "characterizing it as a crime against humanity or a genocide."