Lebanon's Parliament today unanimously endorsed the Israeli-Lebanese peace accords in a major victory for President Amin Gemayel and for diplomatic efforts aimed at achieving a withdrawal of foreign forces from Lebanon.

In Jerusalem, the Israeli parliament voted 57 to 6 with 45 abstentions to endorse the U.S.-mediated accords, which are expected to be signed Tuesday. Virtually all of the abstentions came from the opposition Labor party, which protested that the pact does not set a precise timetable for the return of Israeli forces from Lebanon.

The agreement requires the Israelis to withdraw their estimated 20,000 troops from Lebanon between eight and 12 weeks after the accord takes effect, but it does not specify when the pact becomes effective, according to English-language copies of the pact obtained by The Associated Press here and in Jerusalem. Excerpts from the text appear on Page A9.

Israel has said that it will not pull out its troops until Syrian and Palestinian forces also agree to leave Lebanon. Syria continued its campaign against the agreement, warning today that it would side with dissident Lebanese politicians in a civil war if the accords are signed.

The agreement declares an end to the state of war between Israel and Lebanon and calls for each nation to respect the other's "sovereignty, political independence and territorial integrity." It declares inviolable the existing Lebanese-Israeli international boundary.

If the agreement takes effect, it thus appears that Lebanon would move significantly closer toward recognizing the Jewish state. But the accord stops well short of requiring Lebanon to follow Egypt in granting full diplomatic recognition. It also creates a Joint Liaison Committee with U.S. participation to consider in the six months following withdrawal "the development of mutual relations between Israel and Lebanon" including "the movement of goods, products and persons, communications, etc."

The vote in Lebanon's Parliament strengthened the nation's consensus on the agreement in the face of the Syrian threats. Gemayel technically did not need the vote before signing the accords, but it was seen here as an important gesture of support.

Deputies, who met here amid strict security, were not asked to vote directly on the agreement. Instead they voted on a statement expressing "steadfastness of national unity in supporting the Gemayel administration in achieving full sovereignty."

Despite the parliamentary vote, seven influential Lebanese politicians have formed a "national front" to oppose the accords and have garnered strong Syrian support.

Damascus radio quoted Syrian President Hafez Assad as telling the Lebanese dissidents yesterday that Syria "supports your struggle against the agreement and attempts to infringe Lebanon's independence . . . and isolate it from its Arab surroundings."

Syrian Foreign Minister Abdul Halim Khaddam, in an interview published today in Beirut's leftist As Safir newspaper, said, "This agreement will not pass and will not be implemented, because we will not allow it to be passed irrespective of how matters in the region develop."

Plans here tonight were for formal signing of the accords Tuesday in Khaldah, an Israeli-occupied suburb of Beirut, and in Qiryat Shemona, an Israeli town near the Lebanese border. The long drawn-out Israeli troop withdrawal negotiations had alternated between the two towns.

According to the AP's texts of the agreement, it consists of a main section plus an annex and appendices on security arrangements in southern Lebanon. As noted in previous reports based on leaks about contents of the pact, the accords create a security zone in southern Lebanon running north as much as 28 miles into Lebanon from the Israeli border, the AP said.

The Lebanese government will have full responsibility in the zone for preventing attacks from there into Israel and for guarding against the return of Palestinian or other guerrilla groups that might stage such attacks. But the accords also provide for formation of joint Israeli-Lebanese supervisory teams to visit the security zone "to conduct regular verification of the implementation" of the arrangements.

Lebanon had opposed allowing Israel to maintain any presence in southern Lebanon but yielded in the face of strong Israeli pressure. A Lebanese officer will command each supervisory team, which have power only to contact Lebanese authorities and urge them to take steps to prevent cross-border attacks. The teams may be eliminated upon 90 days' notice by either party at any time after two years following the date that the agreement takes effect.

The annex specifies that Lebanon may maintain two Army brigades in the security zone as well as police and other internal security forces. The appendix lists in detail the weapons permitted Lebanese forces in the zone, including no more than 40 tanks for each Army brigade.

The zone is divided into northern and southern sections, with one Lebanese brigade in each. The brigade in the southern section will include "existing local units," an apparent reference to forces of Israeli-allied militia leader Saad Haddad that will join the Lebanese Army.

The agreement did not specify any role for Haddad himself, a former Lebanese Army major. Israel wanted Haddad to serve as a commander in the south, but Lebanon objected because he faces treason charges for creating his own enclave there and running it on behalf of the Israelis. Officials say that Beirut and Jerusalem agreed separately that Haddad would serve as a deputy commander.

Implementing the accord as a whole will be the responsibility of the Joint Liaison Committee, on which each country will be represented by a senior official. This committee in addition will establish a security arrangements committee to monitor the agreements specifically related to security. This latter committee, which will be responsible for the joint supervisory patrols, will include equal numbers of Lebanese and Israeli representatives headed by senior officers. A U.S. representative also will participate if either party requests.

The agreement allows for one unit of the U.N. peace-keeping force now in southern Lebanon to move to the Sidon area 25 miles south of Beirut to support Lebanese government authority there and protect Palestinian refugee camps.

The agreement does not specify that it will take effect only after Syrian and Palestinian forces agree to leave the country with the Israelis. The relevant clause says: "Within eight to 12 weeks of the entry into force of the present agreement, all Israeli forces will have been withdrawn from Lebanon. This is consistent with the objective of Lebanon that all external forces withdraw from Lebanon."