An independent rights group says Myanmar should give humanitarian aid workers unfettered access to a Muslim village that was attacked last week by a Buddhist mob and end the mass arrest of Muslim men and boys.

Matthew Smith, executive director of Fortify Rights, estimated Thursday that as many as 40 people may have been killed. He says he based his findings on witness testimonies and credible sources on the ground.

The government has repeatedly denied any deaths.

Security forces surrounded Du Char Yar Tan, a village in Northern Rakhine state, on Jan. 14, after Rohingya Muslim residents allegedly abducted and killed a police officer.