The Rohingya refused to show their faces to the 10 visiting investigators, fearing reprisals when they return home, said Bangladesh district administrator Imrul Kayes.
He said the men and women talked from behind a curtain and gave accounts of horrors they faced, including the raping of women, killing of children and burning of villages.
About 35 people described their experiences to the investigators in Cox's Bazar district, he said.
About 90 000 Rohingya Muslims have crossed the border from Myanmar into neighbouring Bangladesh.
Myanmar's army launched counter-insurgency operations in Rohingya areas in northern Rakhine state last October after the killing of nine border guards. UN human rights investigators and independent rights organisations charge that soldiers and police killed and raped civilians and burned down more than 1 000 homes during their operations.
Myanmar's government has rejected the allegations, but promised to investigate.