The Pakistan military is guilty of rights abuses on the Afghan border, using new security laws and a colonial-era penal system to act with impunity, a report by Amnesty International said on Thursday.
The watchdog said the lack of justice was fuelling a rights crisis in the northwestern, semi-autonomous region where Taliban and Al-Qaeda-linked violence is concentrated.
Pakistan's armed forces have arbitrarily detained thousands for long periods with little or no access to due process, said the report, based on interviews with victims, witnesses, relatives, lawyers, officials and militants.
Cases of death and torture have been documented, detainees are not brought before court and relatives have no idea of their fate, sometimes for extended periods of time, said the London-based human rights group.
"Almost every week the bodies of those arrested by the armed forces are being returned to their families or reportedly found dumped across the tribal areas," said Polly Truscott, Amnesty's deputy Asia-Pacific director.
"The government must immediately reform the deeply flawed legal system in the tribal areas that perpetuates the cycle of violence," she added.
Although judges have sought to investigate the fate of people who go missing, Amnesty said no military personnel had been prosecuted for alleged torture, enforced disappearance or deaths in custody.
It demanded the repeal of sweeping powers of arrest and detention given to the armed forces in 2011, and called on the jurisdiction of the courts and parliament to be extended to the tribal areas.
Pakistan says more than 35,000 people have been killed as a result of terrorism in the country since the 9/11 attacks on the United States and that its forces have for years been fighting homegrown militants in the northwest.
Military officials contacted by AFP declined to respond to the claims until they had read the full report.
Amnesty also singled out the Taliban and other militant groups for targeting human rights activists, aid workers, journalists and alleged spies.
It also reported that the Taliban had brutally executed captured Pakistani troops in contravention of international humanitarian law.