Human Rights Watch says Libyan prison authorities should investigate the alleged abuse of a son of former dictator Muammar Gaddafi and other inmates in a Tripoli prison.

In a statement late Monday, the US-based group said a video made available by news website Clearnews apparently showed guards beating Al-Saadi Gaddafi on the soles of his feet during an interrogation at al-Hadba prison. Other prisoners were seen in the background crying out in pain from being beaten as well.

Gaddafi's son has been in pretrial detention since authorities in Niger extradited him to Libya in 2014.

Libya is bitterly divided between rival governments in its east and west. Al-Hadba is under the control of forces allied with the Islamist-backed Tripoli government, which opposes the Tobruk-based internationally recognized government.