HRW however said the refugees often likely did not understand that the data being collected, including photographs, fingerprints and biographic data, could be shared with Myanmar.
Bangladesh has shifted 18,000 refugees out of a planned 100,000 to the low-lying silt island of Bhashan Char from squalid, cramped settlements on the mainland where 850,000 of them live.
Most of them had fled a brutal military offensive in neighbouring Myanmar in 2017 that UN investigators concluded was executed with "genocidal intent".
Hoque said five people were sleeping in a clothing shop when the fire broke out. "Two escaped but the other three were trapped in a bathroom in the shop."
The fire was the deadliest since more than 740,000 Rohingya fled a military crackdown in Myanmar in 2017 that UN investigators concluded was executed with "genocidal intent".
But concerns have persisted, as the UN refugee agency has not been allowed to interview immigration detainees for more than a year to verify their status.