Accused Soviet spy John Anthony Walker Jr. paid retired Navy Radioman Jerry Alfred Whitworth at least $328,000 to hand over sensitive documents and information, a federal grand jury charged here today in an indictment that a prosecutor said showed Whitworth to be a "very significant participant . . . in a very serious conspiracy."

The indictment against Whitworth, 45, set out a series of 15 payments over an eight-year period that he allegedly received from Walker in meetings in San Diego, Hong Kong, the Philippines and elsewhere. It also detailed alleged meetings between Walker and an unidentified Soviet in Washington, Vienna and the Philippines, including some that allegedly occurred after Walker's meetings with Whitworth.

In a separate indictment returned in Norfolk today, a grand jury charged that Arthur James Walker conspired to give information to the Soviets by supplying classified documents on Navy ship repair to his brother, John Walker. That allegedly occurred in 1981 and 1982 after Arthur Walker obtained a job at a private defense contractor in Virginia, the affidavit said.

A government official close to the case said today that more arrests were possible, but that they probably would involve "peripheral" participants. No arrests are expected "in the short term," he said. Four persons have been charged with espionage so far.

The grand jury indicted Whitworth on one count of conspiring with John Walker, a former Navy colleague, to deliver national defense secrets to the Soviets. In Norfolk, Arthur Walker was indicted on seven counts, including conspiracy to supply classified documents.

The indictments and comments by government officials provided contrasting pictures of the roles of the two men who were alleged participants in a spy ring that authorities have said was masterminded by former Navy Warrant Officer John Anthony Walker Jr., 47. Whitworth's participation was said to be far more extensive and potentially damaging than Arthur Walker's.

The alleged ring came to light after John Walker's arrest May 20 on charges that he was supplying the Soviets with secret Naval documents. Since that time, Walker's son Michael, 22, his brother Arthur, 50, and Whitworth, John Walker's sailing buddy who was once stationed with him in San Diego, have been arrested and charged with espionage.

U.S. Attorney Joseph P. Russoniello said here that Whitworth, who was unemployed and living in Davis, Calif., at the time of his arrest June 3, was a "significant player" and the amount of money that he received "reinforces" the gravity of the alleged espionage.

The financial picture has been unclear in previous discussion about the case. FBI affidavits have alleged that John Walker once received $35,000 for delivering documents. Walker's former wife, Barbara, has been quoted as saying he received $100,000 over 10 years from the Soviets. No large amounts of money had been mentioned for the other defendants.

"In terms of numbers of persons involved, this is the largest organized spy network seen in this country since the Rosenbergs Julius and Ethel Rosenberg were convicted of spying for the Soviets in 1953 . In terms of money paid, it is very, very significant," Russoniello said.

He would not say whether any of the money had been recovered.

A Pentagon official close to the case said, based on information from the indictment, Arthur Walker appeared to be a minor figure in the alleged ring's operations. "From what I can see, the potential damage from Arthur is nowhere near that of Johnny Walker or Whitworth," the source said.

A law enforcement source agreed that Arthur Walker had a limited role. "Arthur wasn't calling any shots. He was just going along," the source said.

The indictment did not allege that Arthur Walker provided information while he was assigned to the Atlantic Fleet Tactical School as an antisubmarine warfare instructor. Military officials had expressed fear that in that role, which he held from 1968 until 1973, Arthur Walker might have divulged highly sensitive information to his brother.

How much money Arthur Walker allegedly received remained unclear. An FBI affidavit has indicated he once received $12,000 for his work. Another affidavit said John Walker encouraged his brother to "operate like Jerry, who was making 'big bucks' by photographing classified documents in his van and then supplying them to Walker."

The largest alleged payment to Whitworth, the indictment said, was for $100,000 in June 1980, about the time that Whitworth withdrew his request to resign from active service. Whitworth retired in 1983 as a senior chief radioman and had clearance to see top secret documents, according to Navy records.

The alleged conspiracy between Whitworth and Walker began in "at least April 1976, while Whitworth was petty officer in charge of the Satellite Communications Division at the Naval Communications School at Diego Garcia in the Indian Ocean, and was responsible for the custody of classified material," the indictment said.

It charged that Whitworth had access to "a broad spectrum of sensitive military communications information," including documents, cryptographic key lists and key cards used to encode secret messages, message traffic and operations orders.

Whitworth accumulated such information and periodically delivered it to Walker, the indictment charged. It stated that the men communicated through secret codes, photographed the documents with miniature cameras, and stashed currency in bank safe deposit boxes.

That conspiracy lasted until April or May 1984, about the time that Whitworth allegedly wrote an anonymous letter to the FBI offering to uncover a major espionage ring in return for complete immunity, the indictment charged. Whitworth, who agents have said signed the letter "RUS," later withdrew the offer, according to an affidavit.

An earlier complaint filed against Whitworth had charged that the conspiracy began in 1965. Russoniello said yesterday that prosecutors believe it was "appropriate to proceed on as limited a basis as we can . . . . It's the same conspiracy."

In Norfolk, a separate indictment charged that Arthur Walker, a retired Navy lieutenant commander, twice provided the Soviet Union with classified documents from the defense contracting firm of VSE Corp., where he has been employed for five years developing plans to repair Navy ships.

The first time was in September 1981, the indictment alleged, when John Walker gave the Soviets a confidential "damage control book" for the USS Blue Ridge that was obtained from his brother.

A damage control book is usually a training manual on how to repair damages from battles, fire or collision, Navy spokesman Lt. Cmdr. Bill Harlow said yesterday. The USS Blue Ridge is an amphibious command ship stationed in Yokosuka, Japan, that carries senior naval and marine officers during amphibious operations.

The second instance occurred April 28, 1982, the indictment alleged, when Arthur Walker provided the Soviets with a confidential report on equipment failures on LHA ships, vessels used to transport marines to trouble spots around the world.

The indictment charged that Arthur Walker obtained a job at Chesapeake offices of VSE Corp. in February 1980 in order to have access to secret materials and release them to the Soviets through a conspiracy with his brother.

U.S. Attorney Russoniello declined to specify whether federal agents have uncovered any of the $328,000 Whitworth allegedly received. Search warrants for Whitworth's safe deposit boxes remain under seal.

Whitworth is to be arraigned Tuesday in San Francisco, Arthur Walker Tuesday in Norfolk. Walker will plead not guilty, his attorneys said. Both have been held without bond since their arrests.

Arthur Walker confessed on May 24 to his role in the alleged spy ring, an FBI agent testified at a hearing last week. A U.S. prosecutor in California has said in court that Michael Walker, a seaman on the USS Nimitz, also has admitted he passed documents to his father. Whitworth is not cooperating with federal prosecutors, Russoniello said.

The indictment indicated there were "41 overt acts" by Whitworth and Walker that furthered the alleged conspiracy. Russoniello declined to specify what sources agents had relied on in gathering that evidence.

The Norfolk indictment charged Arthur Walker with one count of conspiracy and two counts of delivering classified documents to the Soviets. Each count carries a maximum penalty of life imprisonment. The indictment also charged him with two counts of unauthorized taking of and two of unauthorized possession of confidential documents.