The United Nation report says that about 8000 loyalist of former Libyan leader are being tortured in the detention centres by militias.
The United Nations human rights chief Navi Pillay has asked Libya\\\’s transitional government to take full control of all prisons.
She said that many detention centres are controlled by militias unaccountable to the government.
Ms Pillay added that her staff has received alarming reports from the Red Cross officials that this is happening in over 60 detention sites that they have visited.
"There\\\’s torture, extrajudicial executions, rape of both men and women", she added.
Rights groups have repeatedly raised concerns about torture being used against people, many of them sub-Saharan Africans, suspected of having fought for Moamar Gaddafi\\\’s forces during Libya\\\’s nine-month civil war.
The groups claim that such incidents are widespread in Libya.
London based Amnesty International state that several detainees have died after being tortured by militias in detention centres.
It said in a statement that, its delegates met detainees held in Tripoli, in Misrata and in smaller towns such as Ghariyan who showed visible signs of torture inflicted in recent days and weeks.
Reports of the mistreatment of Gadaffi loyalists were strengthened by the the international medical humanitarian organisation Medecins Sans Frontieres (MSF) which has suspended its work in Misrata due to the brutal torture of the detainees.
General Director of MSF Christopher Stokes said that "Patients were brought to us in the middle of interrogation for medical care, in order to make them fit for further interrogation. This is unacceptable," he said.
"Our role is to provide medical care to war casualties and sick detainees, not to repeatedly treat the same patients between torture sessions."
Meanwhile, the head of the military council in Misrata has denied involvement of his office in any of the reported abuses and said that the accusers have a hidden agenda.
"There may have been a few cases of former rebels taking revenge but that doesn\\\’t mean that the orders have come from my office to torture prisoners."