Detainees from Libya's war held by fighters continue to be subjected to torture despite efforts by the provisional government to address the issue, according to the UN human-rights chief.
Navi Pillay told the UN Security Council on Wednesday she was extremely concerned about thousands of prisoners, most of them accused of being loyalists of the toppled government of Muammar Gaddafi and many from sub-Saharan Africa.


"The lack of oversight by the central authorities creates an environment conducive to torture and ill-treatment," Pillay said.


"My staff have received alarming reports that this is happening in places of detention that they have visited."
She said it was urgent that all Libya's detention centres be brought under control of the justice ministry and general prosecutor's office and that detainees be screened so that they could be freed or receive a fair trial.
The government that replaced Gaddafi's administration has been struggling to take control of the detainees held by the fighters who overthrew Gaddafi, but has been hampered by lack of prison staff, UN officials say.


Al Jazeera's Stefanie Dekker, reporting from the Libyan capital, Tripoli, said "the government is facing real challenges" in their efforts to "get the jails back under some kind of official control".
"We have to remember that this is an interim period, the country is getting back on its feet and the court systems are not up and running as they should be," she said.
Six jails taken over
Ian Martin, the UN special envoy for Libya, told the Security Council meeting that the Libyan justice ministry had so far taken over six prisons from the revolutionary brigades.
Neither Pillay nor Martin gave any figures for the number of people held by the fighters. Ban Ki-moon, the UN secretary-general, said in a report last November that it was about 7,000.
Abdurrahman Mohamed Shalgham, the Libyan ambassador to the UN, told the Security Council there were more than 8,000 prisoners in Tripoli alone, but did not make it clear if that included people held by the authorities.



He said his government condemned the use of unauthorised detention centres.
"We have spoken to our brothers and we have said, 'Any individual who has not committed a crime, or who has not participated in massacres will have their passports,'" he said.
On allegations that NATO caused civilian casualties during a bombing campaign that helped the fighters overthrow Gaddafi last year, Pillay called on the alliance and other parties to co-operate with a Libya commission of inquiry set up by the UN Human Rights Council.
"Information so far indicates that NATO made efforts to keep civilian casualties at a minimum, but where civilians have been killed and injured, the alliance should disclose information about all such events and about remedial actions undertaken," she said.
Shalgham said Libya was aware of four incidents, but questioned whether NATO was at fault in any of them.
"Without NATO, hundreds of thousands of people would have died in Benghazi", the birthplace of the uprising, he said.