A vice president of CBS News said today he believes the killing last week of two CBS camera crew members in southern Lebanon was not deliberate but resulted from a "tragic error" by the Israeli Army tank crew that fired on a group of journalists.

Ernest Leiser, who was taken near the site of the shooting in Lebanon yesterday, made the comment following a meeting here today with Prime Minister Shimon Peres.

"I came to the conclusion that it was not somebody shooting deliberately at a camera crew," Leiser said in a telephone interview. "It was somebody shooting at what they thought were armed men about to fire at them."

But Leiser said questions still remained over the tank crew's decision to fire before the target had been identified clearly. "It could be a case of someone firing before they could reflect or be sure," he said.

In New York, CBS News President Edward M. Joyce, who last week had called the shooting "an unprovoked and deliberate attack," said that in the light of new information, "it is entirely possible that the tank crew was unable to make out the camera and press signs on the car" of the CBS crew.

But Joyce called it "a matter of regret" that Peres "has elected not to investigate the incident further, and plans no measures which could prevent a recurrence of last week's tragedy."

The two men were killed Thursday in an area where Israeli Army units were searching villages for Lebanese guerrillas.

According to journalists in the group fired on, the two Lebanese employes of CBS, Toufiq Ghazawi, a cameraman, and Bashir Metni, a sound technician, were killed by a shell fired from a tank about 500 yards away. The witnesses said that the group was clearly identifiable as journalists and that the tank appeared to fire at them deliberately.

Based on these accounts, CBS urged an "independent investigation" into what it said appeared to be "deliberate fire by Israeli forces on unarmed and neutral journalists."

During a meeting today with Peres that Leiser described as "amiable," Peres turned down a request for a special investigation but said CBS would be given a summary of the Israeli Army's review of the action. Peres' spokesman, Uri Savir, said Peres "sees the case as closed" and had "expressed regret that CBS jumped to conclusions and issued its original condemnation of Israel before hearing the Israeli side."

CBS already had announced cancellation of special broadcasts here next week in connection with the Jewish festival of Passover and the Christian Holy Week. Leiser said "that decision is not going to be changed," but he denied charges that it was made in retaliation for the killings.

"We had planned a series of celebratory broadcasts, and under the circumstances we don't feel like celebrating," he said.

In its original account of the incident, the Israeli Army said that the tank fired on "armed men who had taken firing positions" and that it had appeared that the television crew members "were among the armed men in the village."

Later accounts by the Army dropped references to the presence of armed guerrillas in the area but contended that from the distance involved it was impossible to distinguish between a man aiming a television camera and a man aiming an antitank weapon.

According to the Israelis, the U.S.-built M60 tank, stationed outside a village being searched at the time, was about 1 1/2 miles from the journalists, not 500 yards as witnesses said.

Yesterday, Leiser and Warren Lewis, the CBS bureau chief in Tel Aviv, were flown by helicopter to southern Lebanon, where they met Brig. Gen. Erwin Levy, the division commander of the units that conducted the searches last week.

Levy briefed the CBS officials on the Army's findings. They were flown to within about two miles of where the tank fired, but could not land because of bad weather. Col. Raanan Gissin, the chief Army spokesman in Jerusalem, who accompanied Leiser on the trip, said Israeli units in Lebanon have standing orders to fire on "moving targets" that appear armed. He said the tank crew spotted what it took to be a group of armed men, but because of the distance it first radioed this information to its battalion commander and got permission from him to fire.

After the first shell, the journalists ran for their cars, Gissin said, and the CBS employes were killed by the second and last shell fired by the tank.

Gissin conceded that the most common antitank weapon used by the Lebanese guerrillas -- rocket-propelled grenades -- could not reach a tank at the distance described by the Israelis. But he said that there are weapons that could and that the tank crew "followed regulations."

Joyce, in his statement, said: "Although all the facts are not clear, two salient points have been clarified: first, the CBS news crew was not among a group of armed men as originally claimed by the Israel Defense Forces. A high Israeli official has indicated that this claim was in error, stating that the tank fired at "a group of people who the Israelis thought was armed . . . .

"Second, it appears that contrary to earlier eyewitness reports, which placed the Israeli tank at 500 to 900 yards away, it may have been a good deal farther, perhaps as much as a mile and a half. If this were the case, it is entirely possible that the tank crew was unable to make out the camera and press signs on the car.

"CBS News is appreciative of the open and cooperative manner in which Prime Minister Peres has dealt with Mr. Leiser and the access he was given to the military in south Lebanon. It is all the more a matter of regret then, that the initial Israeli Army statement on the matter was both distant and unresponsive to our concerns."