After a night of the worst shelling in Lebanon's seemingly endless civil strike, Lebanese President Elias Sarkis said yesterday that he would disband the government and establish a new administration of the country's man political leaders.

While elsewhere in the Middle East the talk of peace as a result of the Camp David agreements, in Lebanon the situation continued to deteriorate at a rapid rate.

"They're firing shells like machine-gun bullets," said one resident. "There has never been anything this heavy."

A spokeman for the main Christian Phalange Party milita said few buildings in its Beirut stronghold remained untouched. A Syrian statement said its men were forced to "fire intensively" to break the siege of a Syrian unit surrounded by militiamen in a Christian quarter.

Rightist sources said 32 persons, mostly civilians, were killed in the overnight shelling and more than 200 injured. This would put estimates of the casualty toll for the last three days at more than 100 killed and as many as 500 injured.

The Syrians have not disclosed their own casualties. Militia sources say the Syrians lost at least 60 men in the same period.

In an emotional address over the national radio, Sarkis said " the latest events left almost no family without a casualty or an undestroyed house. Not one hospital in East Beirut remains which can ensure service for the injured and being displaced from one village to the next."

Sarkis added that he would present a new "emergency security plan" within 10 days, based on "the need for full self-restraint." The new Cabinet of political leaders, he said, would deal wish the present crisis and "save the homeland." Sarkis called for such a cabinet last April but the political factions failed to reach accord and a caretaker Cabinet of technocrats has ruled since.

President Sarkis, a Maronite Chris- tian avoided taking a firm stand to break the deadlock between the Syrians and the militias. He therefore drew fire from all sides, especially from his fellow Maronites.

"The only thing left for Sarkis to do now is to resign," said former president Camille Chanoun,78, chief of the Christian rightist National Liberal Party. The white-haired party [WORD ILLEGIBLE] who also heads the Lebanese Front alliance of hard-line Maronite parties, has vowed to keep fighting until the last Syrian soldier goes home. The Front has received Israeli support.

Throughout Christian East Beirut, hundreds of buildings have been damaged by the bombardments. Many are scarred by shell holes; others stand with their upper stories in ruins. Some have collapsed entirely. Two buildings caved in on their basement shelters, burying an estimated 30 people under tons of concrete. Many structures are blackened by fires from what militiamen said were Syrian amorphorous and incendiary shells.

Broken railings hang from shattered apartement balconies, Severed power cables and telephone lines dangled across streets and parked cars sit muffled with shrapnel or smashed by direct hits. Broken furniture and household goods add to the concrete [WORD ILLEGIBLE] that make streets impassable. In one district, a large uprooted tree [WORD ILLEGIBLE] across a wide road.

Despite the pounding of Saturday night, there was little sign of despair among the militiamen and civilians who remained in East Beirut on Sunday, a tour of the area showed. They are a hardy breed, and they seem more determined than ever to fight to the finish against what they see as as all-out Syrian attempt to Crash Lebanon's dominant Christian minority and control the country.

"It's them or us," said Iskandar. Iskandar, 18, a member of Chamoun's "Tiger" militia. "We want the syrians to try to come and get us, but they won't. They're scared they'll be killed," he said, cradling a M13 automatic rifle with a picture of the Virgin Mary stuck to its butt.

Iskandar said he was one of hundreds of young Christian fighters who have undergone special military training in Israel. He said he went there for the first time when he was 16 and again three months ago.

"We went by boat to Tel Aviv," he said. "Then we were taken to a camp someplace-I don't know where-for commando training. A lot of our guys go."

Israel has also supplied weapons to the militias and has threatened to intervene to stop Syrian "massacres" of the Christian population. But some rightist leaders are starting to feel let down by the Israelis' failure to act during the latest shelling.

[In southwest Lebanon, two formations of six Israeli jets flew over the Palestian-dominated port of Sidon yesterday drawing guerrilla anti-air-craft bursts, United Press International quoted residents as saying. None of planes was hit, they said.]

Another Christian militiaman led me through a maze of alleys, courtyards, gardens and passageways knocked through walls to militia positions near the Rizk Tower, a skyscaper commanding the center of East Beirut. In its upper stories, the Syrians have installed an arsenal of heavy weaponry, including deadly Soviet-made multiple rocket launchers called "Stalin Organs," which they have used to devastate numerous buildings in a wide radius.

Near the Rizk Tower, there are certain places to cross the streets, out of view of Syrian snipers.

"They have a lot of advantages," the militiaman said. "We don't have anything close to the firepower they do, and we haven't got much cover. Also, when we fire at them we can't afford to make any mistakes because our own people are all around."

An artillery commander for his sector, the militiaman said his men were using 106mm recoilles antitank guns mounted in jeeps to fire on the sand bagged Syrian positions in the tower, but that this was not heavy not heavy enough to do much damage.

In a courtyard behind a building some 200 yards from the tower, the militiamen had built three small blockhouses of reinforced concrete to provide cover for three mortars.

Inside the building a militia operations room was arrayed with detailed maps of East Beirut, charts and drafting equipment. on a map, green lines marked several main avenues controlled by the Syrians and orange-colored streets were deemed "no man's land" because of Syrian sniping.

Neither the Rizk Tower nor any other Syrian position was visible from the mortat emplacements in the courtyard. "But don't worry, we have made our calculations and we know where the shells are going, my guide said.

In another neighborhood, a civilian resident strolled with his pregnant wife to inspect the latest damage during Sunday's lull before clashes resumes. "We're staying here," he said. "We're no better than the people who died."

He added: If everyone leaves this town, the Syrian troops can come in. That's part of the Syrians' plan to take over this country."

Residents say up to 70 percent of East Beirut's population of about 600,000 has already fled to safer areas. But those who remain express pretty much the same view:

"I am a Lebanese and I must stay in my country," said landscape designer Marcel Barsoumain, 45. "And I prefer to stay in my own house. If I have to die, it will be here. You can get killed now in the mountains, too."

He was referring to the extension of Syrian shelling Saturday to previously untouched Christian area around Mt. Lebanon and the Metn region, where thousands of city and suburban residents have fled to escape earlier bombardments starting July.

Barsoumal said the latest shelling also marked the first time the Syrians had used such large-caliber artillery as the 240 mm. Several of these shells lay unexploded around East Beirut. Where they had gone off, they dug craters several feet deep.

"With these kinds of weapons, there's no safety in apartments, shelters or anywhere else anymore," Barsoumain said. "If I were in Ain Rummanch or Hadath (two hard-hit Christian suburbs south of Beirut). The damage here is only about 20 percent of what happened there,"