A federal judge Friday postponed the trial of Oliver North in the Iran-Contra affair, ensuring that a courtroom airing of the administration scandal will be delayed until after the presidential election.

In a two-page order, U.S. District Judge Gerhard Gesell granted motions filed by lawyers for independent prosecutor Lawrence Walsh and lawyers for North, who had argued that it was impossible to be ready for trial by Sept. 20, the date originally set by Gesell.The decision to postpone what was sure to be a politically explosive trial is likely to allay at least some of the fears of Republicans that publicity about the Iran-Contra affair would cloud the presidential prospects of Vice President George Bush.

Although Gesell did not set a new trial date, it appeared unlikely that a trial could take place before year's end. The judge gave the parties until Oct. 10 to complete various pretrial interviews and set Nov. 14 as the deadline for North to review hundreds of thousands of classified documents to determine which might be relevant to his defense.

On Thursday, North's lawyers accused Gesell of being in a "frantic rush" to go to trial before the presidential election and asked for a five-month delay in the key pretrial proceeding involving the classified material.

"There is no conceivably legitimate basis for imposing such an obviously impossible burden on the defendant and his counsel," North lawyers Brendan Sullivan Jr. and Barry Simon wrote in asking for the delay.

North is one of four defendants awaiting trial in the Iran-Contra scandal in which profits from arms sales to Iran were diverted to the Nicaraguan Contra rebels.

North, the alleged mastermind in the scheme, was charged with 16 criminal counts, carrying a maximum penalty of 85 years in prison and fines totaling $4 million.

His government supervisor, former national security adviser John Poindexter, was also charged in the conspiracy and faces seven counts carrying a maximum penalty of 40 years in prison and fines totaling $1.75 million. Also facing charges are retired Air Force Maj. Gen. Richard Secord and his Iranian-born business partner, Albert Hakim.

All men have pleaded not guilty.

North, a retired Marine lieutenant colonel who worked on the National Security Council, is expected to call on his former colleagues in the Reagan administration as part of his defense, publicity that Bush hoped to avoid during his campaign against Democratic presidential candidate Michael Dukakis.