The Justice Department will seek to change court rules in an effort to save its prosecution of a sensitive national security case, a senior official said yesterday.

Philip B. Heymann, head of the department's criminal division, made his first courtroom appearance to announce that the government will ask the U.S. Court of Appeals to let prosecutors challenge potentially sensitive evidence before it is introduced by the defense at the trial of Robert Berrellez. Berrellez is an official of International Telephones and Telegraph Corp. who is accused of lying to the Senate about his firm's attempt to influence the 1970 presidential election in Chile.

The Berrellez has been complicated by government fears that defense attorneys migh uncover still secret Central Intelligence Agency relationships in Latin America and make them public during the trial.

Part of the charge against Berrellez is that CIA officers conspired with him to block a 1973 Senate investigation of ITT-CIA collusion during the election of Salvadore Allende.

Prosecutors normally challenge the relevancy of defense evidence after it is presented. But here the government is seeking to make that challenge in advance, Heymann said to assure that national secrets won't be disclosed.

U.S. District Court Judge Aubrey Robinson Jr. refused last week to approve a blanket government proposal for setting up such a procedure. He gave prosecutors will yesterday to decide whether to drop the charges against Berrellez.

Heymann said he would make an uncommon "mandamu" appeal to the higher court, instead, in hopes Robinson would be overruled. The department's top prosecutor said persons can't be given "broad immunity" from charges just because their case might involve classified information.

The significance of the government's effort in the Berrellez case extends to other national security cases as well, Heymann said, because the fear of disclosing secrets is a recuring problem in such prosecutions.

A recent Senate Intelligence Committee study of the tradeoffs in prosecuting national security cases recommanded that Congress consider passing a law to formalize the procedure for advance challenge to defense evidence.

The government also disagreed with Robinson ysterday on two key points for judging the relevance of evidence Berrellez' defense attorney, Patrick A. Wall, might try to present.

Heymann said the court should reject as irrelevant any defense claims that government agents encourage Berrellez to lie or obstruct the Senate investigation. The indictment charges that CIA officer Jonathan Hanke aided Berrellaz and another ITT official in preparing false testimony.

Heymann also said the defense shouldn't be allowed to refer to sensitive material introducing evidence about Berrellez's motives for the alleged perjury. Robinson had said the jury should be able to hear information bearing on the generral background of the defendant's intentions.

Those issues also will be appealed.

Heymann told reporters after the hearing that it is "likely" the government would drop the prosecution if the appeal is not successful. But a department spokesman qualified that statement later, saying it depended on how decisive the appeals court ruling is.

Robinson expressed some sympathy yesterday for the government's concern about some advance determination of the relevance of defense evidence.

Referring too defense attorney Wall, the judge at one point said, "Our problem is he doesn't know what he knows." Another time he told Wall: "Their concern is you have some information that is relevant to you but you don't know how sensitive.

Under the proposed solution that it is."

Justice now carries to the higher court, Wall would tell the judge each time he intended to raise a classified issue and the prosecutors could argue against it inaa secret hearing.

Robinson seemed to agree with the procedure but refused to sign such as order now, before those circumstances arise.