Electronic jamming of Radio Liberty and Radio Free Europe by the Soviet Union is "counterproductive" because "it attracts interest to something that is not all that interesting," Soviet journalist Vladimir Posner said yesterday.

Posner, appearing before a sometimes hostile audience of several hundred at the conservative American Enterprise Institute, said he was speaking personally and not as a spokesman of the Soviet government.

"I feel that jamming is counterproductive. I also feel that the kinds of broadcasts that are being done by Radio Liberty and Radio Free Europe are subversive openly," he said. He added later that by counterproductive he meant it "as a very personal assessment; it attracts interest to something that is really not all that interesting."

Posner, who said he was in the United States to help arrange a televised exchange between citizens of Boston and Leningrad on June 22, has also appeared recently on Phil Donahue and Larry King programs and ABC News' "Nightline."

The Soviet commentator, who grew up in the United States until his family moved to Berlin in 1948, provoked an outcry from conservatives in this country last February when ABC allowed him seven minutes of prime time following a speech on the budget by President Reagan.

Asked whether he appears as an agent of his government, Posner said that before he can appear on U.S. broadcasts, he must receive permission from Gosteleradio, the state Television and Radio Committee. But, he said, "I have never been briefed by anybody, and therefore that is why I say consistently that I am not an agent of the government."

Later, he said, "I would agree with you that if my government did not want Vladimir Posner to go on, he would not." He also said that upon returning to the Soviet Union he will be "debriefed" by government officials and will speak on radio and television about his views of the United States during this trip.

Posner said the withholding of information by his government about the Chernobyl nuclear reactor accident for three days was a mistake. "I don't justify it," he said. "I've said many times it was a mistake. I've also said hopefully we have learned from that mistake."

Posner said that Soviet physicist Andrei Sakharov, in exile in Gorki, could be released if he would refrain from "allowing the Western media to use him against his own country."

He also said that labor camps like those described by Alexander Solzhenitsyn in "The Gulag Archipelago" existed during the reign of Stalin. "I would flatly deny that today those exist," he said, but noted that labor camps are used in place of prisons.

After one listener, former Central Intelligence Agency director William E. Colby, asked Posner whether the Soviets were complying with SALT II, Posner said:

"I don't think that we are in a position to hide that from American intelligence, nor do I think that American intelligence can hide that from us. My impression is that the time has come when this administration [finds it] quite difficult to say, 'We are not going to abide by SALT II because we don't want to,' so you have to find [another] argument. So the argument is that the Soviets are not complying."