Mortar shells fired by the Lebanese Army two miles away in Suq al Gharb exploded with increasing frequency all around this nearly deserted Druze stronghold today.

The crackle of small-arms fire grew in intensity and Lebanese Hawker Hunter warplanes zoomed a few hundred feet overhead, strafing and rocketing Druze positions on the western fringes of the town.

The streets were deserted except for occasional cars traveling at breakneck speed. Inside some houses there were still groups of residents huddled behind sandbags.

On the western side of Alayh, where the shooting and shelling were the heaviest, Anis I. Obeid, a naturalized American cardiovascular specialist who has returned here to help his war-ravaged Druze relatives, showed a group of visiting American reporters his shell-damaged home.

Obeid's house was also surrounded by sandbags but they had not saved the windows, or the roof, which had been virtually destroyed by a shell. Leaves of a vine in front of the house had been seared off by the heat but bunches of ripe grapes still hung from it, waiting for a cease-fire or a lull in the fighting to allow them to be picked.

At the time, we were unaware that the Druze had just launched a tank-led ground assault on Suq al Gharb, although several T55 tanks that had been standing under a bridge near the Druze Progressive Socialist Party office when we arrived to talk with officials earlier were gone when we left.

The Druze we talked to here say they are fighting against the Lebanese Army for the survival of the Druze people.

As the direction of the war has become clear over the last two weeks, several said, hundreds of Druze soldiers have deserted from the Lebanese Army and joined the Druze militia fighting for control of these mountains overlooking Beirut.

Druze officials also say a decision was made Sunday to ask all Palestinian units to leave the front line area and to bar any others from coming to join the fighting.

"We don't want to go to the front and worry about some one behind us working for his own benefit and betterment," said Yasser Haidar, 24, a local Druze official. He said two Palestinian factions had almost come to blows here earlier this month after the Druze victory over the rival Christian Phalangist militia in nearby Bhamdun.

"Our policy nowadays is not to allow anybody else to control our policy," he said. There have been reports that Druze leaders have become increasingly uneasy about the Palestinian role in their fight for control of their Chouf mountain homeland.

Present at the Druze party office, just behind the ridgeline where the fighting has been concentrated, were three former Druze members of the Lebanese Army including an officer, who agreed to be interviewed provided his name was not disclosed.

The officer, a lieutenant who defected just before the Israeli pullback from this area Sept. 4, said it had not been his intention to desert but that "what was happening was wrong." He was referring to the Army's attempt to implant itself in this part of the mountains without the political consent of the Druze.

"I will not bear arms against my own people in an unfair and unjust war," he said. "The Lebanese Army didn't fight the Syrians or the Israelis but now they see fit to fight the Druze. What is the logic?"

"When it becomes the role of the Army to destroy its own people, I cannot do it," he added, warning that if the fighting continued much longer "the Army will fall apart."

Haidar and the chief Druze party official, Akram Shaieb, said that 400 Army deserters had so far joined the Druze militia and that many hundreds of others were trying to cross the lines but were trapped in Beirut.

Later, an Army spokesman in Beirut denied there was any problem of Druze desertions and said the figure of 400 was "not true at all." But he confirmed that Army checkpoints throughout west Beirut are now looking for deserters and armed with a list of names of wanted persons.

Before the onset of the fighting here in the mountains Sept. 4, the 33,000-man Army had about 1,000 Druze soldiers and officers.

It has been a point of pride among Army officials that the Army has not divided along ethnic and sectarian lines and held together under prolonged stress. But there have recently been numerous reports of increasing desertions among both Shiite Moslem and Druze soldiers.

Among the Druze officers who have deserted, according to officials here, were a major, Amin Abu Assi, and a colonel, Riad Takeddine. But most of the deserters, they said, were from the rank-and-file.

Two other Druze deserters from the Army were sitting in a group of militiamen outside the party office and showed their military identity cards as proof that they had been in the Army. They gave the same reason as the lieutenant for leaving the Army--refusal to fight against their own people.

Druze party officials here were candid about the problems the presence of Palestinian fighters has caused them both internally and in their relations with Israel and the United States.

The officials said militiamen manning two checkpoints above Bhamdun on the Beirut-to-Damascus highway had orders to stop any Palestinians trying to come to join the fight. But they admitted it was not always possible to know who was who in similar military uniforms and that some Palestinians might be getting through.

There have been reports that some Palestinians have joined Syrian-backed leftist Lebanese groups aiding the Druze militia.

Haidar also said there was no way the Druze could control what the Palestinians did from behind Syrian lines, such as firing artillery and mortars in their support.

On our return to Beirut this afternoon we saw several artillery guns firing toward Suq al Gharb from Syrian emplacements near Hammana 10 miles east of Alayh but it was impossible to determine who was firing--Syrians, Palestinians or Druze.

At one point, a Lebanese aircraft attacked one of the Syrian-controlled positions, firing rockets into it, and a fire was burning near another one, apparently from an earlier bombardment.

The Druze have been trying to mobilize their own people from around the world. Many have been returning to help as well as to visit their families and friends for the first time since the Israeli Army withdrew from this area.

Obeid, 49, from Syracuse, N.Y., is among those who returned. His parents, he said, had had to be evacuated four days ago after their home was hit by shelling.

Obeid, who said he is a Republican in the United States, said he was deeply concerned America was becoming embroiled in the war here "on the wrong side" and did not realize that for the 200,000 Druze of Lebanon it was a struggle for "mere survival."