JERUSALEM, NOV. 27 -- Five Israeli soldiers and at least two Palestinian guerrillas were killed in a firefight in southern Lebanon early today, continuing what senior officials here say is an incipient revival of Israel's front in Lebanon following the Syrian-enforced end to the civil war in Beirut.

In the fourth encounter between Israeli forces and Arab guerrillas in Lebanon in a week, an army patrol attacked a group of four Palestinian fighters shortly after midnight as it reached the eastern edge of Israel's self-declared "security zone" at Chebaa, Lebanon, about 10 miles from the Israeli border and two miles from Syria, military sources said.

In the ensuing battle, five Israelis were killed and one was wounded, the army said. The army said two of the Arabs were killed and two escaped. Lebanese police told the Associated Press that eight Palestinians were killed.

The Israeli casualties were the army's most severe in Lebanon in more than two years, and followed a week in which four different groups have launched operations against the Israeli-controlled zone. Today's was claimed by the Popular Front for the Liberation of Palestine, a Syrian-backed group in the Palestine Liberation Organization.

Following the clash, Israeli warplanes attacked bases east of Sidon, Lebanon, belonging to two other Palestinian groups, military officials said. They said the planes destroyed their targets and returned safely. Lebanese police told AP two guerrillas were killed in the raid.

Senior Israeli officials said the rash of incidents may augur the revival of southern Lebanon as a Middle East flash point after several years of relative calm. Such a development, they said, could bring Israel back toward confrontation with Syria, now the dominant power in Lebanon and a key member of the U.S.-led alliance against Iraq.

"This may be the beginning of something," said Uri Lubrani, the Defense Ministry's coordinator of Israeli activity in southern Lebanon. "I think the Syrians may want to keep our front, if not sizzling, then active."

In part, Israel's new troubles on the northern front can be connected to the violence that has plagued it internally and along its other borders since the slaying by police of 17 Palestinians during stone-throwing protests near sites holy to both Moslems and Jews in Jerusalem Oct. 8, officials said. Since then, groups such as the Popular Front and Islamic Jihad have launched attacks of revenge.

Israeli analysts say Syria's recent move to break lingering resistance in Beirut to the government of President Elias Hrawi has raised tensions in southern Lebanon, where powerful Palestinian and Lebanese Shiite militias are based, and where Israel controls a 325-square-mile strip of Lebanese land along its border with the help of its 2,500-member South Lebanese Army militia.

Although preoccupied for now with the consolidation of the Beirut area, Hrawi and his Syrian backers have declared their aim of forcing Israel out of southern Lebanon as part of an effort to establish the government's control over the entire country in 1991. Israeli officials say they will not pull out of Lebanon until the area north of their border is secure, and say Hrawi is incapable of establishing control.

For now, the focus of the tensions building between Israel and the Hrawi government is Jazzin, a predominantly Christian town of 20,000 that lies well north of the Israeli security zone -- and about 20 miles north of the border -- but is controlled by the South Lebanese Army. In the past, Israel has said it was not committed to controlling Jazzin, but senior Israeli officials have responded to the developments in Beirut by declaring that Israel will not allow the town to be wrested from the SLA.

In a briefing this week, a senior army official said Israel had drawn the line at Jazzin because it is a strategic crossroads and because the Lebanese appeared intent on making the town into a test of Israeli resolve to remain in the south. However, security sources in Lebanon pointed out that, by insisting on remaining in Jazzin, Israel had placed itself directly in the way of any attempt by the Hrawi government to extend its control to the south.

"Israel clearly does not want Hrawi to succeed, and by holding on to Jazzin, right in the middle of the country, they are helping to ensure that he won't," said a Western diplomat.

The largest militia in southern Lebanon, the 3,000-member Fatah movement controlled by PLO Chairman Yasser Arafat, continues to respect a two-year-old moratorium on armed attacks, officials here said. But the Iranian-backed Hezbollah group has been freed to focus on Israel following the conclusion of a truce with the rival Amal militia, they said.

Lubrani said Israel would be willing to withdraw from Lebanon in favor even of an unfriendly regime there, provided it was willing to set up practical arrangements with Israel to prevent cross-border raids. But he said Israel would probably resist a withdrawal not linked to removal of Syrian forces from Lebanon.