The Israeli Army ceremoniously pulled out of southern Lebanon yesterday and handed over control of the volatile border area to rightwing Christian Lebanon militias as the United Nations peacekeeping forces stayed, reluctantly, in the background.

Just one day short of three months after it swept across the Lebanese border in retaliation for a Palestinian terrorist attack on a tourist bus near Tel Aviv, Israel lowered its flag in this small Shi'ite Moslem village, started up the engines of its armored personnel carriers and conspicuously withdrew to the border one mile away.

The main handover here was a carefully orchestrated media event conducted entirely in English before several hundred curious townpeople. The unlikely setting was on the banks of a mud pond in which a dozen disinterested local women washed cooking utensils and in which sheep and goats drank as florio speeches blared over loudspeaker.

Just as incongruous was the total absence of the U.N. peacekeeping force, to whom Israel was required to turn over territory under a Security Council mandate.

A small U.N. contingent of Irish soldiers drove, seemingly by chance, into the village during the handover ceremony, but it was quickly shooed away by Israeli officers and out of sight of the boards of photographers and television crews.

The lack of a U.N. presence under-scored the peacekeeping officials that Israel has successfully circumvented the United Nations and will retain some control over the border region inside southern Lebanon by proxy, since it has close ties to the Christian Phalangist force and is known to supply it with arms and money.

Reporters with U.N. officials in Lebanon were shown a map with a ink. It ran from the Israeli border very near the coast all the way to the mountains on the Syrian border. For most of its length it was from three to five miles deep and ballooned up to encompass a very large area around Marjayoun.

Maj. Gen. Emmanuel Erskine, commander of the U.N. force in Lebanon, said yesterday that the Lebanese government had recognized the Christian troops are part of its regular army, special correspondent William Branigin reported from Ras el Baya in Lebanon. While this avoided a possible confrontation between the U.N. and Christian forces, Branigin reported, it raises the threat of renewed conflict between the Christians and the allience of Palestinian/leftists and Moslems that battled each other for 18 months in the Lebanese civil war.

[Branigin also reported that the Israelis have turned over 20 of their former positions in the Lebanon to the Christians whil e the U.N. troops are moving into 14 other positions the Israelis held.]

The 5,000 U.N. soldiers who are stretched out along the 62-mile belt running from the Mediterran to the foothills of Mt. Hermon originally occupied by Israel will still have a role in southern Lebanon, but one that is shared with the Christian militias.

The controversy over Isael's decision to hand over the area to the christian rightists was resolved in a meeting late Monday that included U.N. Middle East commander Gen. Ensio Siilasvuo and Israeli Chief of Staff Rafael Eitan. Israeli defense Ministry officials that night began talking about the exclusion of the U.N. force, in an apparent attempt to soften the impact of yesterday's move.

In fact, the Christian militia units, led by Maj. Saad Haddad had been steadily moving into Israeli defense positions for weeks as the Israelis conducted a phased withdrawal. Haddad's flags were seen flying from those position, and the Isaelis defended position, and the U.S. force by saying that they could not give to the U.N. units what was not theirs to give.

A U.N. spokesman in Jerusalem yesterday declined to comment on the turnover by the Israelis, other to say that the Security Council resolution giving the peacekeeping force its mandate specifically requires that Israel give up the border zone to U.N. troops.

The spokesman said that the Israeli Army had agreed to help the U.N. force take up other positions in southern Lebanon before it completed its pullout.

However, Haddad, who seized control of a 700-man garrison of Lebanese troops in 1976 when the Syrian army moved into Lebanon to end the civil war between the Christians and Palestinians, left no doubt as to whom he feels will be in control along the border.

"We are in control of the area and the U.N. is helping us," Haddad said, adding that the international peace-keeping force would be allowed to patrol inside such Christian strongholds as Marjayoun, northwest of here.

Haddad said that his understanding of the U.N. Israel agreement is that his units will control the border area" from the sea to the mountain (Mt. Hermon."

Haddad said the area is now clear of Palestinian guerrillas and that the Christians would depend on Israel to "keep its eyes on the area" to discourage further infiltration in the south.

Hadded also said the U.N. force has a responsible to keep the palestine Liberation Organization out, or "otherwise we hope the Israeli forces will interfere again."

The chief of the Isaeli Army's northern command, Maj. Gen. Avigdan b Ben-Gal, obliquely affirmed Haddad's wishes when he said in his speech, "The Israeli government still insists on her commitment to help the Christian minorities of south Lebanon." He also said the United Nations has a "duty" to prevent terrorist attacks.

The Israeli withdrawal had none of the trapping of a mass evacuation of troops and materiel, since most of the army had pulled back during two earlier withdrawals, leaving behind for its Christian phalangist allies a network of defensive positions and recently paved roads to facilitate supply and support.

Yet the ceremony here, and another similar one in Marjayoun seemed meticurously planned by public relations minded Defense Ministry officials and the army to underscore as much as possible the amicable circumstances of the departure.

Miss EL Jabal was chosen, presumably, because it sustained no damage during the Israeli invasion, and the townspeople who turned out for the ceremony appeared genuinely grateful for the protection they have enjoyed first by the Israeli and U.N. forces and then by Haddad's Christian militias.

The Isaelis had fashioned a crude parade ground next to the teeming mud pond, complete with hastily erected flagpoles flying the Israeli and the Lebanese flag.

When the flag of Israel finally was lowered, the townspeople remained silent, but the Christian militiamen cheered and shouted nationalistic slogans. The Lebanese flag remained raised.

William Branigin filed the following report from Ras El Bayada in Lebanon:

The former Israeli positions the U.N. forces are moving into are not only fewer but less important than the positions the Israelis have be-queathed to their Christian allies.

While the government may have averted a confronstation between the U.N. troops and the Christian rightists by recognizing the Christian as part of the regular army, there is the risk that it may renew the Christian-Palestinian conflict.

The Palestinians and Lebanese leftists had pressured the government to cashier Maj. Haddad and men as a step toward rebuilding a unified Moslem-Christian army. Syria, wh* ich has 23,000 men on peace-keeping duty in Lebanon, is also understood to be opposed to Haddad.

Despite what U.N. spokesmen had called firm assurances of cooperation from the Israelis, an Israeli 20 man unit on duty at a checkpoint refused to let a bus carrying 150 reporters pass.

When Erksine arrived at the scene, reporters crowded near him and Israeli soldier tried to shove the group back with his rifle, forcing Erksine to stumble.

"You're pushing a general!" a U.N. official yelled.

Many observers thought the incident summed up better than words the Israelis' treatment of the U.N. throughout the withdrawal.

One village the Israeli turned over to the Christians, Bint Jbeil, was formerly under Moslem control.