The US-based Human Rights Watch (HRW) is calling for an investigation into the lethal force used by armed groups in the Libyan capital, Tripoli, against protesters, and the subsequent apparent disappearance of some of them.

Libyans took to the streets in late August to protest against corruption, and to demand better public services.

Based on witness testimonies and reviews of photographs and videos, HRW says at least 24 protesters were arbitrarily detained and in some cases tortured by armed groups which are linked to the interior ministry.

The rights organisation says the groups include some of the Libyan capital’s biggest factions – like the Nawasi brigade, and the Special Deterrence Force.

Some people have since been released from detention.

The protests were triggered by persistent electricity cuts and the deterioration of other public services, as well as alleged corruption.

Weapons like machine guns were used to disperse the crowds – one person is known to have died.

At the time, Minister of Interior Fathi Bashagha condemned the violent clampdown and was later suspended by the prime minister pending an investigation.

He resumed his post earlier this month, and it is not clear what the conclusions of the inquiry were.

HRW is calling for an independent investigation into the abuses to be carried out by Tripoli’s General Prosecutor’s Office.