Guantanamo's top security official said Wednesday that intelligence agents had bugged rooms where the accused 9/11 plotters meet with their lawyers, despite a ban on eavesdropping.
Colonel John Bogdan testified that he had only recently learned about cameras, microphones and other electronic equipment initially installed by the FBI and now maintained by the prison camp's J2 intelligence unit.
"They've never been used to my knowledge," Bogdan said on the third day of a preliminary hearing at the US naval base in southeastern Cuba. "Any listening to attorney-client meetings is prohibited, this is a key thing."
He added the electronic equipment was owned by J2, and that the intelligence component was "in charge of replacing it, repairing it, upgrading it."
Defense lawyers have already said that client-attorney privilege has been breached in the case, citing the government's use of microphones capable of eavesdropping on legal conversations held with the five men accused of plotting the September 11, 2001 attacks on the United States.
Bodgan said he had seen two cameras resembling smoke detectors in each of the 16 cells of Echo II, an area of Guantanamo where high-value detainees meet with their lawyers and representatives of the International Committee of the Red Cross.
Earlier in the day, Lieutenant Alexander Homme testified via video link about how communications of so-called "high-level" detainees were handled, saying he felt under pressure when tasked to screen the 9/11 suspects' mail.
Homme said working at Guantanamo involved "immense pressure" from lawyers and military commanders, as well as political considerations.
Cheryl Bormann, an attorney for Yemeni suspect Walid bin Attash, quizzed Homme about access to legal documents that support her client's case to which she did not have access, and instructions relating to control of correspondence.
"There was pressure," said Homme, who no longer works at the prison facility and is a reservist in Florida. "I never read the content of anything that I screened. I recall rejecting a fair amount of documents.
"Anything that was not produced by the attorney would be put in the pile to be rejected."
When pressed by Bormann, Homme conceded that he faced pressure from the US State Department, the Federal Bureau of Investigation and other government agencies.
Homme said he did not "recall dealing directly with representatives of intelligence agencies" other than J2.
The hearing -- which was boycotted by all five 9/11 suspects on Wednesday -- is being viewed by reporters via a live feed shown at the Fort Meade military base in Maryland, near the US capital.
Shortly before the end of the session, lawyers for three of the accused said confidential material had been taken from the cells of their clients during Tuesday's hearing.
"Their cells have been ransacked and legal material has been seized from their cells and are now missing," Bormann said. "A third party is in possession of client-attorney privilege."
Judge James Pohl ordered the materials be returned by Thursday and "not further read."
The suspected plotters face the death penalty if convicted over the attacks against New York's Twin Towers and the Pentagon, as well as the crash of a passenger jet in Pennsylvania more than 11 years ago.