A defense lawyer at Guantanamo Bay in Cuba said Monday that there is "overwhelming circumstantial evidence" that the U.S. government is listening to privileged communications between high-value detainees accused of orchestrating the Sept. 11, 2001, terrorist attacks and their lawyers.

Cheryl Bormann, who represents Yemeni defendant Walid bin Attash, said devices designed to look like smoke detectors and placed in client meeting rooms are in fact audio monitors.

The issue of eavesdropping arose two weeks ago when the audio feed from the courtroom at Guantanamo Bay was mysteriously cut. To the apparent surprise of the military judge, army Col. James Pohl, it was revealed that an unnamed government agency, listening for the potential release of classified information, controlled a "kill switch" to the feed provided to the public gallery and media centers.