A powerful car bomb exploded near the entrance of a Druze meeting house in mainly Moslem west Beirut today, killing two persons and wounding 12 others, as fighting in the hills east and south of the city spread close to the Beirut International Airport.

Battles between Druze fighters and Christian militiamen of the Lebanese Forces raged in the Iqlim Kharroub region in the southern Chouf mountains and along the strategic Suq al Gharb ridge, drawing Lebanese Army troops stationed there into the fighting.

The week-old hostilities have been escalating gradually since Walid Jumblatt, the Druze minister of tourism and leader of the Progressive Socialist Party, denounced a government security plan aimed at sending Lebanese Army troops into the Iqlim region, which runs east into the mountains from the coastal highway south of Beirut between Sidon and Damur.

The booby-trapped car, which the Christian Voice of Lebanon radio said carried about 165 pounds of explosives, punctuated the worst day of mountain fighting in many months.

A bystander said he saw the car driven to an alleyway leading to the meeting house for clerics of the circumspect and secretive Druze sect, a medieval offshoot of Islam, on a hill adjacent to fashionable Verdun Street. The explosion occurred during the evening rush hour and was followed by wailing sirens and machine gun fire.

Jumblatt, the Druze leader, set a bellicose tone last week when he denounced the government security plan to deploy Lebanese Army troops along the coast south of Beirut and in the Iqlim region as a prelude to a wider Army role in southern Lebanon in conjunction with United Nations troops after an Israeli withdrawal.

The flare-up in the hills of the Iqlim and the Suq al Gharb ridge spilled over into residential suburbs of Christian east Beirut over the past two days. Yesterday, the command of the Christian Lebanese Forces said it had decided to retaliate by bombarding Druze strongholds in Shuweifat, just above the airport, and in Chouf villages.

Today, an artillery shell landed in the driveway of the presidential palace in Baabda, outside east Beirut, while President Amin Gemayel was chairing a Cabinet session that was boycotted by Jumblatt.

Jumblatt has said he supported sending the Army to southern Lebanon but vowed that he would not let it encircle his men in the Iqlim. "If the Army wants to go to the south, let it. But it will not be allowed to set up positions between Khaldeh and the Awwali River," the northernmost Israeli defense line, he warned.

After a meeting with Jumblatt and his key aides today, however, Education Minister Salim Hoss told reporters that "there was unanimity on opening the coastal road."

The mounting tension in the Iqlim came to a head when Druze gunners of the Progressive Socialist Party, who control the coastline from Khaldeh to Damur, closed the port of Jiyah north of Sidon. Jiyah has been the Christians' only link between Beirut and Christian villagers and militias in the Iqlim.

The Druze party's military spokesman, Anwar Fatayri, declared that the Druze would never allow the Jiyah port to reopen and said its closure meant "farewell to all security plans." Christian sources said the retaliation of the Lebanese Forces yesterday was intended to reduce pressure on Jiyah.

Although Jumblatt has denied allegations that he was planning to create a Druze autonomous region in the Chouf and the Iqlim, there are fears that Christians driven from about 70 villages in the region after Druze-Christian fighting there in September 1983 may never be allowed to return.

Naoum Farah, the spokesman of the Lebanese Forces, charged tonight that the Druze wanted to deprive Christians of their only sea link between Beirut and the Chouf. Farah urged the Sunni and Shiite Moslem communities to oppose Jumblatt's course of action, which he said threatens Lebanon's unity.

Nabih Berri, the Shiite Moslem minister for southern Lebanon, has accused the Israelis of being behind the intensification of violence in recent weeks. Lebanese officials are concerned about a possible partial Israeli pullout, hinted at in the Israeli press recently.

No progress was made yesterday at Israeli-Lebanese military talks as Lebanese negotiators insisted on a major role for the Army and reiterated their rejection of a mission for the Israeli-backed South Lebanon Army.