(CNN) -- Armed militias in Libya are committing human rights abuses with impunity, threatening to destabilize the country and hindering its efforts to rebuild, Amnesty International said Thursday.
Militias have tortured detainees, targeted migrants and displaced entire communities in revenge attacks, according to a report the organization released a year after the start of popular uprisings that eventually ended Moammar Gadhafi's 42-year rule.
"Hundreds of armed militias, widely hailed in Libya as heroes for their role in toppling the former regime, are largely out of control," the report says.
Detainees at 10 facilities used by militia in central and western Libya told representatives from Amnesty International this year that they had been tortured or abused. Several detainees said they confessed to crimes they had not committed in order to stop the torture, Amnesty International said.
At least 12 detainees held by militias have died after being tortured since September, the human rights organization said, adding that authorities have not effectively investigated the torture allegations.
"A year ago Libyans risked their lives to demand justice," Donatella Rovera, a senior crisis response adviser at Amnesty, said in a statement. "Today their hopes are being jeopardized by lawless armed militias who trample human rights with impunity. The only way to break with the entrenched practices of decades of abuse under (Gadhafi's) authoritarian rule is to ensure that nobody is above the law and that investigations are carried out into such abuses."
Libyan officials could not be immediately reached for comment.
A spokesman for the Tripoli Military Council told CNN on Wednesday that civilian leaders in Libya must do more to assert their authority, holding accountable militia members who perpetrate abuses.
"If the Libyan state is being built, these guys who committed this need to be brought to justice, whether they are revolutionary fighters or not, otherwise the whole world will ask, 'What changed in Libya?' The same systemic abuse and torture is continuing, and this is dangerous for the new Libya," council spokesman Anes Alsharif said. "The only solution is for the government to take over. You can not let these guys keep holding the prisoners."
Civilian authorities have been slow to step in, Alsharif said, even though some prisoners have been held for months without facing official charges.
"When you talk to the government they say, 'keep them, we don't have time yet.' and this is wrong," he said.
A process for government takeovers of prisons has begun, Libya's interim prime minister said in a televised address last month.
Libya's ambassador to the United Nations, Mohammed Shalgham, told the United Nations last month that Libya does not approve of any abuse of detainees and was working to stop any such practices.
Libyan Interior Minister Fawzy Abdilal told CNN this month that the country's interim government had not yet succeeded in integrating militias from different cities into a national security force.
Other organizations have also raised concerns about the militias.
The medical charity Doctors Without Borders said last month it was halting its work in detention centers in Misrata because detainees were tortured and were denied urgent medical care.
Human Rights Watch said earlier this month that the torture and killing of detainees is an ongoing practice among Libyan militias and will continue unless the militias are held to account.
CNN's Jomana Karadsheh contrbuted to this report.