Oliver North's Iran-Contra trial came to a halt again Tuesday after it was discovered that government-censored memos by North's Contra courier, Robert Owen, had already been made public.

North's lawyers immediately moved to dismiss the indictment against North, saying it was impossible for the former White House aide to get a fair trial under federal secrecy procedures.U.S. District Judge Gerhard A. Gesell sent the jurors home, saying there were "unresolved" problems concerning the classified material. He scheduled an afternoon hearing on the matter.

"We are dealing with problems inherent in the nature in this trial: what is classified and what isn't classified," said North lawyer Brendan Sullivan. He said the matter was "so extraordinary and so important it affects the ongoing nature of the trial."

The dispute was triggered by a memo by Owen, which stated the name of a high Costa Rican official, former security minister Benjamin Piza. Owen's memo containing Piza's name had already been turned over in a lawsuit to the Christic Institute, an activist group, that has been critical of U.S. policy in Central America.

However, when the same document was introduced at North's trial, Piza's name had been excised by U.S. intelligence officials on national security grounds.

The disclosure that the name had been turned over to the institute last summer caused Gesell to call for the hearing.

"We have reached a point where I have to take some testimony relating to legal matters," he told the jury. "I did not realize this situation confronted me until I arrived at 7 o'clock this morning."

Owen was North's courier to the Contra rebels in Nicaragua and was being cross-examined by Sullivan. Owen was to appear at Tuesday afternoon's hearing.

North's lawyers filed a motion asking that the indictment against North be dismissed on the ground of "misconduct" by the prosecution.

They alleged in the motion that the office of independent counsel Lawrence Walsh had known for at least 10 days that all but one of 19 memos by Owen to North introduced in the case had previously been turned over to the Christic Institute.

"Instead of disclosing this critical fact, the IC (independent counsel) hid it and, incredibly, insisted that the court and the defense treat these already-public documents as classified," the motion said.