The Justice Department asked the Supreme Court Saturday to delay former White House aide Oliver North's Iran-Contra trial, citing a danger he would divulge too many secrets.

"Proceeding with the trial on those terms will make it impossible for the attorney general to fulfill his responsibility to safeguard classified information," the department said in asking for a stay.Independent counsel Lawrence Walsh, who is prosecuting North, urged the Supreme Court to reject the Justice Department's request, saying the department has no legal authority to seek a delay.

Walsh said the attorney general "comes before this court in an attempt to assume a role that the Ethics in Government Act and his own Independent Counsel Regulation deny him: that of prosecutor in this case."

The independent counsel called the Justice Department request an "11th-hour application" and said the department "has sought to interfere in this trial at the final hour."

A jury was chosen Thursday in North's trial on 12 felony charges stemming from the Iran-Contra affair and U.S. District Judge Gerhard A. Gesell has asked the jurors to report to the courtroom Monday.

It was not clear when the Supreme Court was likely to act on the Justice Department request; the court is in recess until Feb. 21.

The Justice Department appealed to the Supreme Court after a three-judge federal appeals panel on Friday - for the second time in as many days - refused to delay the start of North's trial.

Department officials say that if the delay is denied, Attorney General Dick Thornburgh is prepared to act under the Classified Information Procedures Act to file an affidavit objecting to disclosure by North of some classified information. That step could result in dismissal of some or all criminal charges against North.

Under CIPA, once the attorney general files an affidavit, the court must order North not to disclose the classified information at issue, even though it is relevant material tending to prove his innocence. Dismissal of charges likely would follow on grounds that North would not be given a fair trial.

The department criticized the judge in the case for not reining in North's plans to use extensive amounts of classified material.

"No order of the District Court prohibits defendant North, in his opening statement or during the government's case, from simply disclosing, without seeking prior court approval, classified information that falls outside" eight categories identified by Gesell last Wednesday, said the Justice Department's 19-page court filing.

"Even as to information within those categories, no order prohibits defendant North from disclosing classified information during his own case," it added.

Gesell issued orders Dec. 12 and Jan. 19 spelling out how much censorship could be applied to classified material that the prosecution and defense planned to use at trial.

"The categories of information covered by the two orders were by no means exhaustive," said the Justice Department. "Much classified information remained unprotected and was not the subject of any pretrial ruling on admissibility."

The department wants to delay the trial so additional steps can be taken to bar North from disclosing classified material.

Walsh disagreed with the department's assessment, saying he believes that "all areas of concern to the intelligence agencies have been adequately covered by the district court's orders."

The independent counsel said that during seven months of CIPA proceedings he has asked intelligence agencies to enumerate which specific classified information could never be disclosed at trial, and then took action accordingly to protect the secrets.