Convicted spy John Anthony Walker Jr., and possibly some members of his family, will testify at the espionage trial of Jerry Alfred Whitworth, prosecutors said yesterday.

In papers filed in federal court in San Francisco, prosecutors said Walker would testify that he spied for the Soviets from 1968 until his arrest May 20, and that Whitworth, his Navy colleague, joined the conspiracy in 1974.

Walker pleaded guilty to espionage Oct. 28 and promised to testify against Whitworth, one of his closest friends and the remaining defendant in the Walker spy ring case.

Lawyers for Whitworth, a retired Navy communications specialist, have asked U.S. District Judge John P. Vukasin to block other members of Walker's family from testifying against their client.

The family members they mentioned included two other members of the spy ring: John Walker's brother Arthur James Walker, a retired Navy lieutenant commander who was convicted of espionage Aug. 9, and John Walker's son, Navy Seaman Michael Lance Walker, who pleaded guilty to espionage in October.

Defense lawyers James Larson and Tony Tamburello also asked the judge to bar testimony from John Walker's ex-wife, Barbara Joy Crowley Walker, and his daughter, Laura Walker Snyder, who alerted the FBI to John Walker's spying.

In papers responding to the motion, Assistant U.S. Attorney William Farmer did not state that the government planned to call the various members of the Walker family to testify. However, he refused to rule out that possibility and argued that their testimony should be permitted if they are summoned.

Vukasin granted a defense motion yesterday to delay the trial from Jan. 13 until Feb. 10 to give lawyers more time to prepare. Whitworth, 46, was indicted for the fourth time in the case earlier this month on charges of receiving $332,000 from Walker in return for passing secret Navy documents from 1974 through 1985. He is also charged with tax fraud and failure to pay taxes on the money he allegedly made from spying.

Among other evidence prosecutors plan to use at Whitworth's trial, the government papers said, are several pages of handwritten notes by Walker and Whitworth seized from Walker's Norfolk home that "contain sensitive classified information relating to Navy communications systems, including cryptographic systems in use and planned."

A hearing is scheduled Monday on defense requests to block prosecutors from using various items of evidence at the trial, including a "Dear Friend" letter from Walker to his Soviet contact in which Walker allegedly referred to Whitworth by his code name of "D," and a "Dear Johnnie" letter from Whitworth to Walker. Both were found with a package of classified documents that Walker left under a tree in Poolesville, in western Montgomery County, shortly before his arrest May 20.

The defense lawyers also want Vukasin to bar the use of letters sent to the FBI from a person who identified himself as "RUS" and offered help in uncovering a "significant espionage system" in return for immunity from prosecution. The government contends that "RUS," who eventually withdrew his offer of cooperation, was Whitworth.