Accused spy Jerry Alfred Whitworth wants to testify at his upcoming trial on charges of helping convicted spy John Anthony Walker Jr. pass sensitive Navy documents and information to the Soviet Union, defense lawyers said in court papers.

The disclosure was made in support of the defense lawyers' attempt to separate the eight espionage charges against Whitworth from five federal income tax-related counts, and to have the two cases tried separately.

In papers filed in federal court in San Francisco this month, Whitworth's lawyers said the retired Navy communications specialist "wishes to testify concerning the espionage charges but not the tax and fraud allegations."

If the two sets of charges are not separated, Whitworth, 46, would open himself to cross-examination about the tax charges if he chose to take the stand and testify about the espionage counts.

Defense lawyers James Larson and Tony Tamburello did not elaborate on why Whitworth wanted to limit his testimony to the espionage charges. They said forcing Whitworth to explain his reasoning "in open court will necessarily amount to a waiver of his right against self-incrimination."

They asked U.S. District Judge John P. Vukasin Jr. to permit Whitworth to submit papers for inspection only by the judge to explain why "he has both important testimony to give concerning one count and a strong need to refrain from testifying on the other."

In addition to Whitworth's desire to take the stand, defense lawyers argue that combining the espionage and tax charges would result in "undue prejudice" to Whitworth and that the "two sets of offenses are logically, factually, causally and legally distinct."

In court papers filed Tuesday, prosecutors opposed splitting the cases. They argued that holding two trials would be unnecessary and wasteful.

Whitworth is the last of four Navy men accused in the Walker family spy ring to stand trial; two pleaded guilty to espionage and a third was convicted. Whitworth is accused of conspiring to commit espionage with John Walker from 1974 until Walker's arrest May 20. He is charged with passing the Soviets classified Navy information, including cryptographic key cards and keylists used to encode sensitive communications, and technical manuals and plans for the design of the coding machines.

His trial, which is expected to last eight to 10 weeks, is scheduled to start in San Francisco next week.