The Kremlin's chief spokesman, discussing Western claims that recent Israeli military successes in Lebanon were due to use of superior U.S. technology, said tonight that Syria's Soviet-armed forces had destroyed about 100 Israeli tanks and "up to 40 aircraft" in last month's fighting in the Bekaa Valley.

"The Israeli blitz has failed," Leonid Zamyatin said on a prime-time television interview program. Commenting publicly for the first time on the Western speculation that U.S.-made arms were better than Soviet ones, Zamyatin said it represented an element of Israel's psychological and propaganda drive against the Palestinians and Arab countries.

The spokesman acknowledged that Syrian losses were "higher" than those suffered by the Israelis but said that this was due "not to the weapons" supplied by the Soviet Union but to military advantages always enjoyed by an attacker. Zamyatin said the Israeli government was deliberately "minimizing" its losses.

When asked about Zamyatin's statement about how many Israeli tanks and planes had been lost, an Israeli Army spokesman said, "You know that's a lie," Washington Post correspondent Edward Cody reported from Tel Aviv.

Israel so far has announced the loss of one jet fighter and one helicopter in the fighting with Syria, while claiming to have shot down 80 Syrian Migs. It seemed unlikely that the Israelis could cover up the loss of high numbers of aircraft, because pilots and families would spread the word, Cody reported.

Israel has not announced any loss figures for its tanks, and the Army spokesman again declined to do so. Most of Israel's casualties appear to have been suffered in the tank battles with the Syrians, however.

Zamyatin did not elaborate on the performance of Soviet arms in the Lebanese crisis. The official news agency Tass, however, quoted "participants" in the battles as saying, "Soviet tanks, infantry, combat vehicles, antitank guided missiles and artillery have demonstrated well their efficiency."

Zamyatin attributed Israeli advances during the first three days of their lunge into Lebanon, which began June 6, to the fact that forces of the Palestine Liberation Organization were not adequately armed to halt the blitz by Israeli tanks.

"The Palestinians did not expect this attack," he continued. "It was a surprise, sneak attack. They did not have weapons to repulse tanks. They had only light weapons, mostly defensive weapons."

The Israelis, Zamyatin said, had indicated that they would not engage Syrian forces before they attacked the Soviet-supplied SA6 Syrian antiaircraft missile batteries in the Bekaa Valley.

"But on the ninth of June, when the Israelis reached" that area, "you had a real battle" involving the Syrian contingent in Lebanon, he noted.

Zamyatin said the Israelis deployed electronic countermeasures from Israeli territory to "blind" Syria's antiaircraft installations both in Syria and in the Bekaa.

He also charged, without giving any details to substantiate his allegations, that Israel has engaged in "chemical warfare" against the Palestinians, citing the use of a "paralyzing nerve gas" against PLO guerrillas in southern Lebanon.

In its dispatch, Tass said "trained crews of Syrian tanks" each destroyed "four and more tanks of American and Israeli production." It said one Syrian tank brigade in the course of one engagement in the southern Bekaa Valley destroyed "up to 50 aggressor tanks and much other combat equipment." Tass said Syrian antitank forces "in two days of fighting" put out of action 70 Israeli tanks and armored personnel carriers.

The agency said Israel attained "a limited military success" by its sudden and massive attack on lightly armed Palestinian guerrillas and on "a rather limited antiaircraft defense force of Syria in Lebanon." The Syrian units in the Bekaa Valley "were isolated from the main forces located on Syria's territory," it said.

"It is to be noted that Israeli planes did not violate a single time the airspace of Syria," the agency added, recalling "heavy losses" that Israel's Air Force suffered in the 1973 Middle East war.

In an effort to explain heavy Syrian Air Force losses this time, Tass said the Syrians "did not have a ramified network of radar stations, and that complicated their actions."