The Soviet prosecutor of Alexander Binzberg yesterday unexpectedly asked for less than the maximum sentence of 10 years' imprisonment and five of internal exile against the dissident leader.

The prosecuter instead of sought eight years in prison and three of internal banishment during remarks he made toward the close of the third day of Ginzburg's trial for anti-Soviet agitation and propaganda, being held in the provincial city of Kaluga, 110 miles south of here.

Officials said closing statements in the Ginzberg trial could be expected today and a verdict tomorrow.

In the espionage and treason trial of Jewish dissident Anatoly Scharansky, a closed-door session ended in which testimony was heard on charges that Scharansky passed military secrets to an American journalist, and the court began hearing evidence on the lesser charge of anti-Soviet agitation and propoganda.

The rare gesture of recommending less than the harshest possible sentence against a political dissident came as Secretary of State Cyrus Vance and Soviet Foreign Minister Andrei Gromyko opened two days of talks in Geneva on strategic arms limitations, the most crucial current issue between Moscow and Washington.

The simultaneous scheduling of the Ginzberg and Scharansky trials the same week as the Geneva talks has been seen here as a direct rebuke to President Carter for his outspoken support of Soviet human rights activists.

There is no guarantee that the judge and two lay assessors hearing the Ginzberg case will accept the prosecutor's recommendation.

Few observers here believe that the Soviet leadership begins such political trials without having carefully decided well in advance precisely what the outcome will be - even down to the term of sentence. Thus, any move toward leniency, however slight it may seem in the West, takes on possible wider importance.

Both Ginzburg and Scharansky clashed with judges at their trials yesterday, according to Leonid Scharansky, who was present at his brother's afternoon session here, and dissidents and Western correspondents outside the site of the Ginzburg trial.

Describing his brother as "tired but quite disciplined," Leonid Scharansky said Anatoly argued with his principal accuser, Sonya Lipavsky, and other prosecution witnesses who were brought back for testimony against him on the anti-Soviet agitation and propaganda charge.

In Kaluga, Ginzburg and his lawyer, Elena Reznikova, were interrupted repeatedly by the presiding judge, it was reported, when they tried to question prosecution witnesses or make statements defending the 41-year-old human rights activist. Ginzburg's wife Arina was again barred from the trial. She was expelled yesterday after calling a prosecution witness a liar in court.

Ginzburg's mother, Lyudmilla, told reporters after the session that much of it was taken up with marking some 1,800 items for evidence, a process so boring that some of the hand-picked spectators packing the court slept, she said.

Ginzburg was convicted in 1968 on the same charge and thus faces a maximum of 15 years' prison and exile instead of the 12-year maximum for first offenders.

In a group of recent cases, dissidents have received maximum penalties. These include Yuri Orlov, confounder with Ginzburg of the Moscow group to monitor Soviet compliance with the human rights provisions of the 1975 Helsinki accord on European security signed by the Kremlin; Jewish activist Vladimir Slepak; and Ukrainian dissident leader Mikola Rudenko.

A principal witness against Ginzburg has been Arkady Gradobovey, a twice-convicted robber who has testified that Ginzburg and his dissident friends were criminals because they listened to the Voice of America and read the books of Alexander Solzhenitsyn. Solzhenitsyn was a close friend of Ginzburg's before the Nobel-Prizewinning author was exiled by the Kremlin in 1974, after several year's harassment.

Ginzburg later administered a relief fund for political prisoners from Solzhenitsyn's royalties. The judge reportedly urged Gradoboyev to speculate as to whether Ginzburg misused any of this money. Reporters who asked court officials later about this and other personal allegations against Ginzburg were told it was in line with the prosecutions's contention that his activities and habits were destructive of the state.

Ginzburg has been denied requests to allow defense witnesses to appear.

Yesterday morning's session of the Scharansky trial was closed on secrecy grounds, a court spokesman said. A statement from the court trying the 30-year-old computer programmer said experts, presumably KGB agents, reviewed the documents used by the prosecutor to prove treason. It was ruled that the "information on the U.S.S.R. defense industry and its installations which Scharansky is said to have forwarded to the West, is absolute secret and constitutes a state secret."

Statements were read into the record signed "by a foreign correspondent, a witness questioned during preliminary investigation who cooperated with the military intelligence service of a capitalist state." This is the official description of Robert Toth, a Los Angeles Times reporter once based here. He has been accused of being a CIA spy - Part of an espionage ring of Soviet dissidents and American diplomats and reporters. Toth has denied the charge.

The official court statements have never identified any American by name or nationality, despite the fact that the original accusation against Scharansky in Izvestia last year named three U.S. diplomats as well as several journalists. One veteran Western diplomat said, "Only the Soviets know why they are doing it this way."

The signed Toth statements were extracted from him by KGB agents during questioning about his ties with Scharansky.

In the afternoon, Leonid Scharansky was admitted to his brother's trial, although the defendant's mother, Ida Milgrom, 70, was barred for the third straight day. She wept at the police barricade, and later accused the government of deliberate "cruelty, torture of a mother." She has not been allowed to see Anatoly Scharansky since his arrest March 15, 1977.

The second trial session turned away from the treason charge, for which he could be sentenced to death, to the anti-Soviet agitation charge, which carries a maximum penalty of 12 years in prison and exile.

At this session, Scharansky again confronted his principal accuser, Lipavsky. Leonid Scharansky said Lipavsky stared straight at his brother and that Scharansky was repeatedly interrupted and lectured by the judge when he sought to counter Lipavsky's accusations of activities harring the state.

Soviet authorities refused to transmit film of the scene outside the Scharansky trial for the ABC or NBC television networks yesterday. A state television official told the networks' representative: "We will not provide any facilities today or tomorrow because of the anti-Soviet campaign abroad. We will not help with that campaign." The films were sent to the West via regular commerical flights, instead of being transmitted via telecommunications lines to Western Europe for satellite relay to the United States.