The appearance of a three-jeep Lebanese Army patrol in a Moslem Druze mountain village outside Beirut today touched off an angry melee in which two Druze civilians were killed and four soldiers were injured.

The military patrol reportedly had gone to the area to prepare for Lebanese Army deployment there after the planned withdrawal of Israeli soldiers from the mountains overlooking the capital.

When villagers learned that the Army was approaching, a hostile crowd of more than 1,000 poured onto the highway to block their advance, according to reports from the scene. The crowd reportedly stoned the soldiers, broke the windows of their jeeps and set tires ablaze on the highway.

The driver of one of the jeeps reportedly panicked and drove into the crowd, killing two and seriously wounding two, prompting firing from all sides. An Army spokesman said one of the four wounded soldiers was seriously injured.

Lebanese Defense Minister Issam Khoury denounced the attack on the patrol as a "treacherous stab against the nation's legitimacy" and said the government would track down and punish "all those responsible."

The violence outside the troubled town of Alayh appeared to be a serious setback to the Lebanese government's hopes of extending authority beyond the capital and its suburbs.

Since last fall neighboring Druze and Christians in the mountains have clashed in battles, snipings, revenge kidnapings and artillery duels rooted in disagreements and hatreds more than a century old.

Israeli forces frequently have attempted to mediate the conflict. They also have been accused by Western diplomats as well as Druze and Christians of fanning the flames, favoring one side, then the other. Israeli authorities have vehemently denied the allegation.

With Israeli forces planning to leave the mountains for new defensive positions in southern Lebanon, the Druze fear that the Christian-led Lebanese Army will favor the Christians in the sectarian disputes.

Druze leader Walid Jumblatt has demanded that there be a political agreement before the Army is deployed in the mountains. He and aides have indicated that they want a say in which officers are sent for duty there and have demanded revisions in Lebanon's political system to give Druze more power.

If there is no political agreement, Jumblatt warned in an interview in Amman, Jordan, this week, Druze forces will fight the Lebanese Army "endlessly."

An official of Jumblatt's militia said they were not involved in today's clashes, and witnesses concurred.

Efforts at reaching a political compromise have been attempted for weeks but reportedly have been stymied by the strong personal animosity between Jumblatt and Lebanese President Amin Gemayel, scions of major Lebanese political families that have long been at odds.

Gen. Ibrahim Tannous, the head of the Lebanese Army, has held several meetings with Jumblatt aides and other Druze leaders as has Gemayel. Tannous is described by diplomats as fearing that if the political issues are not resolved, deployment in the mountains could split his Army along sectarian lines repeating the experience that shattered it in the 1975-76 civil war.

He has reportedly advised patience and hard work in resolving the political issues and counseled against retaliating against Druze in May when they struck at Christians by shelling urban eastern Beirut.