A report into torture by the US Central Intelligence Agency (CIA) will remain classified after a judge claimed it could endanger "national security".
Washington, DC Judge Beryl Howell ruled on Thursday that the report "does not qualify as a public record subject to the common law right of public access."
She said a previous court case had decided that document was a "congressional record" and therefore not open to Freedom of Information Act (FOIA) requests.
"The Report contains highly classified information about the CIA’s detention and interrogation policies and procedures that would compromise national security if released, far outweighing the public’s interest in disclosure," Howell wrote in her opinion.
Attorney and law professor Kel McClanahan, representing investigative reporter Shawn Musgrave who brought the case, vowed to appeal the ruling.
The Senate report runs to 6,700 pages, detailing the inhumane methods used on prisoners held for years, often at the CIA's discretion, beyond the US borders and out of its legal jurisdiction.
Democratic Senator Dianne Feinstein released a 14-page summary of the report in 2014 with a list of 20 findings. Those included the fact that the use of torture had mostly failed to produce useful intelligence, but that the CIA had repeatedly lied to exaggerate its usefulness.
It also found that the "enhanced interrogation" methods used were far more violent than the agency let on, and that they had been developed by psychologists to maximise the victims' suffering.
Feinstein said on Thursday that while she agreed with parts of the Judge's decision, she also believed that the full report should eventually be release "with appropriate redactions".
"The use of torture by the American government was a dark mark on our history that must never be allowed to happen again. We must continue to learn from our mistakes, and that means eventually releasing the torture report at an appropriate time," Feinstein said.
The use of torture by the CIA at so-called 'black site' prisons in other countries, following the September 11, 2001 terrorist attacks, has been widely reported.
The most infamous is the Guantanamo Bay naval base in Cuba, occupied by the US against the wishes of the island's government since the 1959 revolution.
Al-Qaeda leaders and others were held at the base's 'Camp Delta' facility without charge for years, where they were subjected to sensory deprivation, extreme cold and heat, 'waterboarding' or simulated drowning, along with force-feeding when they went on hunger strike.
Some had no connection to the terrorist group. Shaker Aamer, an immigrant to the UK, was working for a charity in Kabul in 2001 when he was detained by authorities there. He became one of the first to be sent to Guantanamo in February 2002.
UK citizen Moazzam Begg was seized by Pakistani intelligence agents at a house he was renting in Islamabad in Februray 2002. He was handed over to US occupation forces in Afghanistan, who held him at the notorious Bagram Air Force for three years before transferring him to Guantanamo.
*Al Qaeda is a terrorist organization banned in Russia and many other countires