Federal prosecutors in the espionage trial of retired Navy communications expert Jerry Alfred Whitworth must prove that Whitworth knowingly spied for the Soviet Union or intended to harm the United States, a federal judge in San Francisco has ruled.

In a major victory for the defense, U.S. District Judge John P. Vukasin Jr. ruled Wednesday that he would instruct the jury that the government is bound to prove that Whitworth passed Navy secrets to confessed spy John Anthony Walker Jr. with the intent or reason to believe that it would aid the Soviet Union or injure the United States.

Prosecutors have asked Vukasin to reconsider the ruling, and a hearing on the matter is scheduled for today. They told Vukasin that, if he does not change his mind, the Justice Department has authorized them to seek to have the ruling overturned by a federal appeals court.

Vukasin's ruling could be of critical importance for Whitworth's defense, which hopes to convince the jury that Whitworth did not know the material was going to the Soviets.

Prosecutors have argued that the government is required under the espionage laws to show only that Whitworth knew or had reason to know that the sensitive Navy secrets he allegedly passed to Walker would injure the United States or help some other country, not necessarily the Soviet Union.

Assistant U.S. Attorney William S. Farmer argued in a hearing Wednesday that the references to the Soviet Union in Whitworth's indictment were designed to provide the defense with adequate notice of the government's case but were not necessary elements for a conviction.

Vukasin said initially that he was inclined to agree, prompting defense lawyer James Larson to say he would be left "essentially with nothing to argue to the jury." Vukasin later changed his mind.

Closing arguments in the case against Whitworth, the last of four Navy men charged in the Walker spy ring to face trial, are expected to start Monday, although they could be delayed by the dispute over jury instructions.

Whitworth, 46, is charged with eight counts of espionage and five counts of failing to pay income taxes and tax fraud involving $332,000 that he allegedly received from Walker.

He is accused of giving Walker copies of Navy codes and design manuals for coding machines that would have permitted the Soviets to eavesdrop on supposedly secure Naval communications.

Walker, the star witness against Whitworth, testified that he never told his Navy colleague that the material Whitworth supplied was going to the Soviet Union. He said he suggested that his buyer was an allied country, such as Israel, or a private organization, such as organized crime or the publication Jane's Fighting Ships.

However, Walker also testified that he believed Whitworth knew the Soviets were involved. In addition, the prosecution introduced letters to the FBI offering to expose a Soviet spy ring in which the writer said he was involved. Prosecutors contend that the letters were written by Whitworth