Human rights activists have slammed the correctional officers of Nusakambangan prison island in Central Java after a video of them mistreating inmates went viral on social media.

The footage was posted on Instagram account @lambe_turah and showed prison guards dragging bound and handcuffed inmates across the dirt, some of whom could be seen with wounds across their back.

According to Kerobokan Prison warden Tony Nainggolan, some of the inmates in the video had been transferred from Kerobokan in Bali to Nusakambangan on March 28.

“They were healthy when we handed them over to the [Bali] police, who then took charge of their transfer to the Nusakambangan Police,” Tony said as quoted by tribunnews.com. “I can make no further comments on this matter.”

In response to the video, the Law and Human Rights Ministry’s corrections directorate general has removed the Nusakambangan Narcotics Prison warden.

 “We are condemning the violent act [and] inhumane treatment of inmates, as per the United Nations Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment [UNCAT], which has been ratified by Indonesia,” Anggara, executive director of the Institute for Criminal Justice Reform (ICJR), said in a written statement received by The Jakarta Post on Friday.

The institute encouraged the Law and Human Rights Ministry, as well as its corrections directorate general, to launch an investigation to address the issue.