The US government destroyed a so-called CIA “black site” with a trial judge’s approval, according to accusations made by defence lawyers for the alleged 9/11 attack plotters.

Defence attorney Cheryl Bormann said that the secret prison, or “torture chamber”, as she called it, was “decommissioned” by US agents, according to a report by the Miami Herald.

Prosecutors were allowed to see top secret photographs and blueprints of one site in question instead of viewing the foreign held US prison in person to “exercise our own professional judgment as to what to document about the black sites,” according to defence attorney Jay Connell.

By substituting photographs and blueprints, the prosecution, led by Army Brig Gen Mark Martins, would not risk divulging the secret location of the site and “court processes don’t squander national security and secrets”. The process of substitution was created by Congress’ Classified Information Protection Act and continued in the Military Commissions Act.

Confessions of a Guantanamo guard Show all 7 1 /7 Confessions of a Guantanamo guard Confessions of a Guantanamo guard U.S. Army Military Police escort a detainee to his cell within Camp X-Ray Getty Confessions of a Guantanamo guard Watchtower security teams at Camp X-Ray man positions and keep a watchful eye over the camp Getty Confessions of a Guantanamo guard A woman walks through a tented area at the U.S. Naval Base, in Guantanamo Bay, Cuba, 18 January 2009 EPA Confessions of a Guantanamo guard 'We did not receive any kind of special training for working at Guantanamo. No one in the company knew what was really going on' said former Guantanamo prison guard Brandon Neely of his time serving at Camp X-Ray AP Confessions of a Guantanamo guard Guantanamo detainees wearing orange jump suits sit in a holding area as military police patrol during in-processing AP Confessions of a Guantanamo guard A suspected al-Qaida or Taliban detainee from Afghanistan is carried on a stretcher before being interrogated by military officials at the detention facility Camp X-Ray on Guantanamo Bay AP Confessions of a Guantanamo guard Items given to Guantanamo inmates upon entry include: two buckets, an orange jumpsuit, boxer shorts, a water canteen, a pink towel, a light sheet, Halal meals (in silver packets), comfort items (Froot Loops, peanuts, energy bar) a bottle of water, a white towel, Quran, shampoo, toothbrush, soap, flip-flops and a foam type mat AFP

Defence discovered that the classified “no-name motions” had requested permission to destroy the black site. The case, they thought, had been stalled in July 2014, until learning that the site had been decommissioned in Feb 2016.

Nevertheless, prosecution maintained they had not done anything wrong by allowing the decommissioning of the site – which involved removing “fixtures” from walls, described vaguely by defence as “contraptions or devices”.

The location of the prison remained kept under wraps during the Sunday hearing.

“We’re not going to let an individual criminal defendant ... mortgage the whole future of the country in one case, because they’ve got something that could force government officials to try to figure out how to accommodate it,” Gen Martin said. “We’re not allowed to compromise national security just to get to a result in a case. That’s what Congress is trying to prevent.”

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The defence are representing five men – led by Khalid Sheik Mohammed, the alleged 9/11 mastermind – who they say were held at the decommissioned site at some point prior to prosecution.

In the Sunday hearing, the defence also accused prosecution of holding a secret meeting with the judge, Col James L Pohl and consider the decommissioning of the site to be destruction of evidence.

Four of five defence teams have asked that Col Pohl remove himself from the case. The only attorney who is not requesting his recusal is motioning to remove the death penalty from his client’s possible sentencing.

The decommissioned secret prison was part of a larger international network of CIA-run “black sites” hosted by foreign countries. Two of the sites were held on the Guantanamo base in Cuba.