The rutted back road to this besieged Druze town three miles south of the capital, the only one still open to traffic, is difficult and dangerous and at the end stands a shell-battered and deserted suburb waiting for a cease-fire.

Located at the bottom of the Chouf mountains where Druze militia and the Lebanese Army are now slugging it out, Shuwayfat has become crucial to both sides because it controls one of the main access routes into the capital.

The Army has imposed a 21-hour curfew around it, and every person going in or coming out is photographed from three directions and has his or her Lebanese identity card photocopied.

"We are looking for Palestinians and Syrians," explained the Army officer interrogating travelers to find out why they want to go into the town. Only residents of Shuwayfat are allowed to pass, and even a Druze taxi driver from a nearby village requires special permission to get in.

Each Lebanese identity card is checked against a computerized list in Beirut of false names and cards that Palestinians or Syrians may be using. If any name matches a person passing here he or she will be arrested the next time through, the officer added.

The process takes so long that few residents managed to get in or out during the 9 a.m. to noon period the road was open today. At noon, a long line of men and women was still standing patiently outside the hut where the Army officer was checking identities.

The Lebanese Christian Maronites have raised a hue and cry about the Christian townspeople and 25,000 refugees besieged in the Druze-encircled town of Deir Qamar in the southern Chouf. But the Druze now seem to have their own besieged town in Shuwayfat, which is surrounded by the Lebanese Army and Christian Phalangist militia and defended by only a few score Druze militiamen.

The big difference is that only a few thousand of the 60,000 residents normally living here have remained. The others have fled to Beirut, since the road to the mountains is now cut by the Army.

"We are being imprisoned either here or there Beirut ," Adel Saab, head of the Shuwayfat Women's Association, complained. "Here we are not safe and there we are not safe. We are suffering as much as the Christians are."

Local media reports say there are now 150,000 persons displaced by the "mountain war," which began as a struggle between Phalangist and Druze militias for control of the Chouf and has ended in a stalemated battle between the Druze and Lebanese Army for a few strategic points.

But this figure for the number of refugees may well be low. Here in Shuwayfat, probably 55,000 people have fled the nightly shelling from the Army and Christian militia that punctured holes in houses, set cars afire, cut electricity and telephone lines and crippled the water supply.

Only a few persons could be seen in the debris-littered streets here today, most of them fetching water from two fountains still functioning or scurrying to buy food from two or three stores still open.

A motley array of Druze militiamen, most of them bearded and wearing bits and pieces of military uniform, sometimes with cowboy hats, were guarding the empty buildings and streets and holding off the advance of Phalangist forces poised 500 yards away at the northern outskirts of the town.

Strangely, a high percentage of Christian families have stayed on and seem to have no fear of their Druze neighbors despite the massacres of Christians in some mountain villages of the Chouf.

Christians and Druze here alike ascribe their good relations to the fact that the Phalangist militia, which tried to move in just after the Israeli invasion in June 1982, was forcibly kept out of Shuwayfat.

In one building, five Druze and five Christians sat together in the living room of the Marabieh family talking to this reporter about their hopes and fears. It was a mixture of old men and women and young children, one sporting a "Popeye" shirt and a cowboy pistol.

Malvina Wahbeh, sick and frail at 80, said she was born here and had no intention of leaving, even in these trying times. "We don't want to leave our homes," she said. "Our Druze neighbors are like our children."

Loris Marabieh, 67, another Christian, insisted she too will not leave but readily admits she is afraid every night of the "bombs." As to the future, "only God knows," she shrugged.

In every group of Druze it seems there is an American connection and Shuwayfat, even largely deserted, was no exception. One in this group was Dr. Aref Abdul Baki, a biochemist educated at the universities of Michigan and California and for 15 years an employe of the U.S. Agriculture Department in Washington. A naturalized American, he returned here 15 months ago to serve as a scientific adviser to the Lebanese government.

Abdul Baki and Mrs. Saab's son, Rabiah, are the only doctors left in Shuwayfat looking after the nightly victims of the shelling and shooting. Among them, according to Abdul Baki, was a 6-year-old child who was killed, with six others wounded, when one of the first shells fired by U.S. warships off the coast fell on a house here.

Abdul Baki, like so many other American-educated Druze, cannot understand why U.S. troops are shooting at and killing his people. He was both angry and ashamed at a turn of events that has pitted his adopted country against his kin.

"If the Americans want to maintain their authority in the Middle East," he lashed out, "certainly they are following the wrong road."

The brief visit was interrupted by the worried Druze taxi driver, who warned that there were just 15 minutes to go before curfew. The shelling, he had heard from the militiamen, was about to start again.