Accused spy John Anthony Walker Jr. urged his older brother to find a job in which he would have access to classified information for sale to "friends who would pay" for it, an FBI agent testified yesterday.

During a conversation in January 1980, John Walker and his brother, retired Navy lieutenant commander Arthur James Walker, referred to those friends as "the Russians," FBI agent Beverly Andress testified at a hearing in federal court in Norfolk.

The next month, Arthur Walker started work as an engineer with a Chesapeake, Va., defense contractor, and has confessed to giving his brother classified documents from the company in 1982, Andress said. She said Arthur Walker admitted receiving $12,000 in exchange for that information, which John Walker told him was delivered to the Soviets.

Federal Magistrate Gilbert R. Swink in Norfolk ordered Arthur Walker, 50, held without bond, saying he found "overwhelming" evidence of probable cause to prosecute Walker.

In other developments yesterday related to the case in which the Walker brothers, John Walker's son, and a Navy colleague of John Walker's have been charged with espionage:

* White House spokesman Larry Speakes said that President Reagan "firmly" supports moves to cut the number of people cleared to see classified information.

Speakes' statement came the day after Defense Secretary Caspar W. Weinberger ordered an immediate cut of 10 percent in the 4.3 million military and civilian employes with security clearances, and Navy Secretary John F. Lehman Jr. said he wanted to cut in half "as soon as feasible" the number of Navy personnel with access to classified information.

* Weinberger, commenting on the Walker case, joined other top administration officials in calling for the death penalty for convicted spies. Such criminals "should be shot, though I suppose hanging is the preferred method," Weinberger said in an interview with wire service reporters.

No change in the law, however, would apply retroactively to the men arrested in the Walker case, who face maximum penalties of life in prison.

* John Walker's lawyer, Fred Warren Bennett, withdrew a request that FBI Assistant Director Bill Baker be held in contempt of court for comments about the case in an interview with The Washington Post.

At the hearing for Arthur Walker, Assistant U.S. Attorney Tommy E. Miller said the case would be presented Monday to a grand jury in Norfolk. An arraignment was scheduled for Tuesday, and Arthur Walker's lawyers said he would enter a plea of not guilty.

Andress testified that Arthur Walker admitted to FBI agents on May 24, four days after his brother's arrest on espionage charges, that in 1982 he signed out a confidential file from VSE Corp. and showed it to John Walker on his lunch hour.

The "casualty report," as the document was called, detailed equipment breakdowns on LHA class ships from 1976 to 1980, she said.

LHA is the Navy's designation for amphibious assault ships used to take Marines to distant trouble spots. Knowledge of equipment problems on such ships could help the Soviets determine the Navy's readiness to transport Marines, according to Navy officials.

Andress testified that John Walker photographed part of the file that day. He took the photographs in the back of a van either in the VSE parking lot or close by, the FBI said.

Arthur Walker returned the file to the safe but kept some of the computer printouts to photograph that night at the offices of his brother's Virginia Beach detective agency, Andress said. The next day, April 29, 1982, he signed out the file again and replaced the documents, she said. "Between the two of them it was possible they had photographed the entire thing."

Andress' testimony hinted that the brothers had well-established procedures for transferring information. She said Arthur Walker would leave rolls of film for John Walker "and subsequently would contact his brother and let him know what was on the film."

FBI agent Robert W. Hunter, who also testified at the hearing, described Arthur Walker as "an expert in antisubmarine warfare" whose knowledge and experience "could be of great value to any hostile power."

But Samuel Meekins, one of Arthur Walker's two lawyers, argued that Walker did not now possess any information that would be of current interest to the Soviets. He said during Walker's 20-year Navy career, he dealt only with diesel-powered ships that are now "outmoded."

J. Brian Donnelly, the other defense lawyer, argued that the government had not proved that the information in the "casualty report" file "was in fact injurious to the nited States" or presented any evidence that "it was communicated to the Soviets."

Meekins, in trying to persuade the magistrate to release Walker on bond, cited his service as a Little League coach and president of his neighborhood civic association in Virginia Beach. Walker, he said, had led efforts to build a neighborhood swimming pool and establish a neighborhood crime watch program.

In the interview, Weinberger said a Pentagon committee was studying the possibility of changing the Uniform Code of Military Justice to make espionage by military personnel punishable by execution even during peacetime. Under current law, the death penalty can be imposed on military employes for wartime espionage. There is no section in the military code dealing with spying at other times.

"I think a peacetime espionage section will be added without any question," Weinberger said. "Whether or not a death penalty is attached to that will be a matter of examination and study."

Navy Secretary Lehman and Assistant Attorney General Stephen S. Trott called on Congress Tuesday to make espionage a capital crime under civilian law as well.