One lawyer for Guantánamo detainees said he replaced his office telephone in Washington because of sounds that convinced him it had been bugged. Another lawyer who represents detainees said he sometimes had other lawyers call his corporate clients to foil any government eavesdroppers.

In interviews and a court filing Tuesday, lawyers for detainees at Guantánamo said they believed government agents had monitored their conversations. The assertions are the most specific to date by Guantánamo lawyers that officials may be violating legal principles that have generally kept government agents from eavesdropping on lawyers.

“I think they are listening to my telephone calls all the time,” said John A. Chandler, a prominent lawyer in Atlanta and Army veteran who represents six Guantánamo detainees.

Several of the lawyers, including partners at large corporate law firms, said the concerns had changed the way they went about their work apart from Guantánamo cases. A lawyer in Chicago, H. Candace Gorman, said in an affidavit that she was no longer accepting new clients of any type because she could not assure them of confidentiality.