Israeli warplanes shot down a Syrian jet attempting to intercept them late this afternoon during a raid on Palestinian positions in Lebanon.

The downing of the jet seemed certain to raise tensions further between Israel and Syria, which are already at loggerheads over the recent stationing of Syrian missiles in Lebanon's followed by one day the reported end of a "misunderstanding" between Israel and the United States on the use of U.S.-supplied military equipment stemming from the Israeli raid last month on Iraq's nuclear reactor.

Today's action also appears likely to complicate the delicate mission of U.S. special envoy Philip C. Habib, who is seeking to head off an Israeli-Syrian confrontation over the missiles. Habib is in Saudi Arabia, having already visited Lebanon and Israel on his third tour of the area since May.

The Israeli Army command said the Israeli jets attacked Palestinian guerrilla ammunition depots and training bases on the Mediterranean coast south of Damour and near Nabatiyeh, in southern Lebanon, and that the Israeli pilots reporting scoring "accurate hits," Washington Post correspondent William Claiborne reported from Jerusalem. An Israeli Army spokesman said the Palestinian facilities were "temporary," and included tents and hastily erected huts.

The Army refused to identify the type of Israeli aircraft used in the raid. Normally such sorties are conducted by F4 Phantoms, with F16 or F15 fighters flying overhead in a protective screen.

The clash with the Syrian Mig was the first Israeli-Syrian dogfight since Feb. 13, when one Mig was shot down over Lebanon. On April 28, Israeli jets shot down two Syrian helicopters used to support Syrian Army attacks on Israeli-supported Christian militias in the Sanin mountains. Shortly afterward the Syrians moved surface-to-air missiles into the region.

[The Israeli Army command said the Syrian Migs today intercepted the attacking Israeli planes after they had completed their mission. The Army command denied a report by the Voice of Palestine Radio in Beirut that an Israeli plane was hit by antiaircraft fire, Claiborne reported.]

Lebanese reporters who witnessed the incident said two Syrian Mig23s engaged in a dogfight with four Israeli F15s between Sidon and Jizzin, 12 miles to the east. They said one of the Syrian planes was hit by an air-to-air missile and exploded in mid-air. One report said the Syrian pilot was killed.

[In a statement issued in Damascus, the Syrian government admitted losing the plane in what a military spokesman termed a dogfight with a "formation of hostile planes" over Lebanon, Reuter reported.]

Initial Palestinian reports on the Israeli raids, the third in the past five days, said six guerrillas and Lebanese villagers were killed and another 35 wounded.

The private radio station of the Christian Phalangist Party in eastern Beirut said eight American-provided Israeli warplanes -- six Phantoms and two F15s -- were involved in the attack along the coast, which apparently lasted less than an hour. It said another eight Israeli jets took part in the raids on Palestinian sites around Nabatiyeh.

The Phalangist radio later reported that ground-to-air SAM missiles had been fired at the Israeli planes but did not say whether they were Syrian or Palestinian. There was no confirmation of this report, however.

Israel ceased all raids against Palestinian bases inside Lebanon in early June for about five weeks, but since Friday it has raided every other day, either in the Nabatiyeh or Damour areas, or now both.