MIAMI, JAN. 11 -- Prosecutors in the drug-trafficking case against former Panamanian leader Manuel Antonio Noriega took the witness stand today and were grilled by defense lawyers about use of government recordings of Noriega's prison telephone conversations.

The highly unusual examination came as the defense sought to prove that the government acted improperly and used taped telephone conversations between Noriega and his defense team to pursue new leads and pick up inside tips about defense strategy.

The defense team sparred with the tight-lipped prosecutors for most of the day, extracting very little to bolster its claim. But U.S. District Judge William M. Hoeveler continued the hearing until next Friday when defense lawyers said they would produce Jose Blandon, a former Noreiga aide, to contradict today's testimony.

Hoeveler, expressing impatience, set a new trial date of June 24 for Noriega, who has been imprisoned for more than a year, and warned the defense to settle other issues relating to their fees.

"I don't want to be ugly about it," Hoeveler said, "but I've got to say we've been at this a long time. The defendant has a right to be tried."

The latest twist in the case began in November when Cable News Network reported that the government had been taping Noriega's telephone calls from Miami Metropolitan Correctional Center to his mistress, his mistress's mother and various political cronies in Panama.

CNN said the government also taped privileged attorney-client conversations involving Noriega.

Today's hearing was punctuated with comical exchanges between the flamboyant defense team and the stern-faced government lawyers, clearly uncomfortable at having to submit to interrogation by their adversaries about government conduct.

Assistant U.S. attorneys M. Patrick Sullivan and Myles Malman acknowledged that they issued eight subpoenas between Feb. 8 and Aug. 1 for tapes of Noriega's prison conversations. Drug Enforcement Administration agents investigating the Noriega case took the tapes to their office here.

Sullivan said the tapes were screened first by an officer at the correctional facility, then by a Chicago-based DEA agent before being turned over to agents working the Noriega case, to prevent them from hearing privileged conversations that may have been taped.

Sullivan outlined in a memo last March 6 procedures to ensure that agents on the case would not be exposed to attorney-client conversations.

But, Thomas Raffanello, a DEA agent supervising the Noriega probe, testified that the Chicago agent worked on the tapes for only about two weeks.

In June, prosecutors acknowledged, the government brought in Blandon, a key government witnesses, to decipher coded phrases used by Noriega on the telephone.

Blandon listened to 22 tapes, prepared a six-page handwritten synopsis in Spanish and sent it by fax to the DEA here.

Blandon is under investigation by the FBI for a possible role in the CNN tape controversy, and his lawyer has indicated that Blandon may invoke the Fifth Amendment right against self-incrimination when he takes the witness stand next week.

Steven Grilli, the DEA agent who worked most closely with Blandon, testified today that he did not read Blandon's fax but had it translated into English, copied and distributed.

Sullivan received a copy and discovered that it contained a privileged conversation. "When I came to the part of Noriega talking to his lawyers, I stopped," he testified.

Frank Rubino, Noriega's chief defense lawyer, asked Sullivan to explain how he could know that it was an attorney-client conversation if he had stopped reading.

The prosecutor explained quietly that "it was noted" on the report.

Sullivan's concession that he had simply stopped reading the report was the first time the government had offered that version of events. In its 31-page response to the defense motion for dismissal, the government did not offer that explanation.

But under questioning from Rubino, Raffanello testified that the chief prosecutor was concerned that Blandon had overhead an attorney-client conversation:

Q: Did Mr. Sullivan have a concern that Mr. Blandon might be listening to conversations between Gen. Noriega and his attorneys?

A: Yes, on that one particular tape.

Special correspondent Jon Leinwand contributed to this report.