Tripoli — ARMED groups in Libya, some affiliated to the government, are accused of murder and other human rights violations against thousands of civilians they have detained .
The United Nations (UN) Human Rights Office said bodies of hundreds of individuals taken and held by armed groups had been uncovered in streets, hospitals and rubbish dumps.
Some bodies had bound limbs, marks of torture and gunshot wounds.
This is the latest crisis in the restive North African country suffering tribal clashes and political crises.
The UN rights organisation said men, women and children were randomly detained or unlawfully deprived of their liberty based on their tribal or family links and perceived political affiliations.
Victims have little or no recourse to judicial remedy or reparations, while armed groups enjoy total impunity.
UN High Commissioner for Human Rights, Zeid Ra'ad Al Hussein, said the UN report laid bare the sheer horror suffered by the victims and their families.
"These violations and abuses need to stop and those responsible for such crimes should be held fully to account," Al Hussein said.
Armed groups on all warring sides have rounded up suspected opponents since renewed hostilities broke out in 2014.
Some 6 500 people are estimated to be held in official prisons.
There are no statistics for facilities run directly by armed groups.
"These facilities are notorious for endemic torture and other human rights violations or abuses," Al Hussein said.
Libya has suffered a series of crises since Muammar Gaddafi was overthrown in 2011.