Image caption The start of the trial could still be a year away

The judge overseeing a military trial at Guantanamo Bay has ordered an end to secret government censors after courtroom sound was cut during a discussion about CIA prisons.

Army Col James Pohl ordered an unnamed government agency to remove censorship equipment, as a second round of pretrial hearings finished on Thursday.

The order could add further delays to the proceedings, correspondents say.

Defence lawyers want assurance talks with their clients were not tapped.

The judge said in his ruling that he had sole authority to decide when to close a hearing or stop spectators - including journalists and relatives of the victims - from listening to testimony.

Spectators watch the proceedings behind soundproof glass, and receive audio on a 40-second delay so that a court security officer can switch on a white noise machine while classified information is being discussed.

No 'unilateral decisions'

But on Monday, the white noise machine was activated without the prior knowledge of the judge or the courtroom security officer.

The interruption came as a defence lawyer referred to a secret, overseas CIA prison where the defendants were held before they were brought to Guantanamo Bay.

Later, the judge decided the information was not secret and released a transcript of what was said.

Prosecutors said the courtroom audio was suspended by an OCA - Original Classification Authority - which could refer to any agency responsible for the classified information at stake.

"This is the last time that an OCA or any other third party will be permitted to unilaterally decide that a broadcast should be suspended," Col Pohl said in his order.

Defence lawyers also filed an emergency motion on Thursday asking to halt proceedings until they can be sure officials were not eavesdropping on communications with their clients.

The five defendants, including Khalid Sheikh Mohammed, face death penalty charges that include murder and terrorism for their alleged roles in planning the 9/11 attacks.

Col Pohl did not rule on the defence lawyers' request, but said it would be addressed at the next session, scheduled for 11 February.

"This needs to be resolved before anything else," he said.

Meanwhile, a range of other legal issues that remain unresolved must be dealt with before the case can proceed to trial.

The four-day hearing was concerned with procedural matters, such as the rules for calling witnesses and handling classified evidence.