The United States yesterday proposed the immediate establishment of a U.N. peacekeeping force for southern Lebanon that would replace Israeli troops in a six-mile-deep swath of territory Israeli has seized in the past few days.

An American resolution placed before the U.N. Security Council called on Israel "to immediately cease" all military actions in southern Lebanon "and withdraw its forces from all Lebanese territory." It envisioned the U.N. peacekeeping role as assuring the return of "effective authority in the area" to the Lebanese government.

The council was expected to vote on the resolution today. American officials, who were involved in protracted negotiations to reach general agreement on the document yesterday, said that council approval was virtually certain.

The U.S. formula to end the Lebanese crisis was advanced on the eve of Israeli Prime Minister Menachem Begin's trip to the United States.

Begin's scheduled arrival in New York today had provided a degree of urgency to U.S. efforts to reach a broad consensus on a U.S. Peacekeeping force before the Israeli leader begins his talks with President Carter in Washington on Monday.

American officials explained the urgency by stressing that they did not want the U.S.-Israeli talks to bog down in the discussion of the Lebanese problem at the expense of fundamental issues involved in a comprehensive Middle East settlement.

State Department officials last night expressed hope for "quick action" by the council. U.N. spokesmen said preparations for a U.N. peacekeeping force were already underway in case the 15-nation council approves the U.S. resolution.

The great powers are excluded from participation in the U.N. force by the U.S. proposal, which specifically mentions that U.N. forces could not be drawn from the five permanent council members.

Israel, while not rejecting the American proposal, has indicated scepticism about the effectiveness of a U.N. peacekeeping force.

When they invaded southern Lebanon four days ago in retaliation for last Saturday's Palestinian raid on Israel, the Israelis said they would remain in the area until an adequate security force was created to keep Palestinian guerrillas from returning to the swath of territory adjacent to Israel's northern border.

Israeli diplomatic sources suggested yesterday that Israel might raise certain objections should the U.S. proposal be adopted. "Our enthusiasm (for the resolution) is limited," these sources said.

The Israelis do not oppose the idea of a buffer zone policed by U.N. forces, but they are questioning the effectiveness of such an international force in preventing Palestinian guerrillas from re-entering southern Lebanon.

The American resolution was submitted to the U.N. secretariat after protracted consulations. Apart from discussions with major Western allies, U.S. diplomats have met with representatives of the Soviet Union and various Arab countries seeking a consensus that U.S. Ambassador Andrew Young said would hopefully result in Security Council action before Begin and Foreign Minister Moshe Dayan started talks with Carter on Monday.

In formally introducing the resolution last night, Young said the American proposal would "prevent further escalation of violence and thereby facilitate the return to peace negotiations."

The Security Council debate on the Lebanese situation was delayed for almost four hours yesterday afternoon when two council members raised objections to parts of the U.S. plan. The objections reportedly focused on the question of Lebanon's sovereignty.

The American resolution, as outlined by Young, called for "strict respect for territorial integrity, severeignty and political independence of Lebenon." Lebanon's approval of the U.N. action as well as its temporarty duration were emphasized. The resolution said the U.N. role would be terminated as soon as security in southern Lebanon was established.

It also called on U.N. Secretary General Kurt Waldheim to report within 24 hours "on the steps taken" to implement the resolution. The document's reference to the return of southern Lebanon to the "effective authority" of the Lebanese government indicated that the U.N. peacekeeping role would be taken over by reconstituted units of the Lebanese army.

There were no indications about the duration of the "interim" U.N. role, although some diplomatic sources suggested that it should last until Lebanon's army was ready to resume control.