Red Cross ambulances evacuated 29 more Palestinian casualties from the embattled Burj al Barajinah refugee camp here today as residents told of food and water shortages that have driven them to slaughter cats and drink from sewers.

Shiite Moslem militiamen, who attacked the camp and two others two weeks ago to keep the Palestinians from reestablishing a military stronghold here, pulled five wounded Palestinians from the ambulances as they left the camp. They were freed later after strong protests by International Red Cross officials and leaders of the Shiite Amal militia overseeing the evacuation.

Food and water shortages and a breakdown in hygiene are posing severe health problems at three refugee camps on the outskirts of Beirut, a Palestinian spokesman said today. In Shatila, he said, 12 children have died in recent days of an undetermined disease.

Medical sources said at least one person has died of typhoid, and they expressed fears that epidemics could spread rapidly in the devastated camps, which still house about 25,000 refugees, if special sanitary precautions are not taken soon.

Sana Saab, director of the Kamal Jumblatt Hospital, where the Palestinians evacuated today were taken, said they had arrived "in a terrible state, very sick and humiliated."

"Several told me residents in Burj were slaughtering cats and eating dry, rotten bread because they had run out of supplies," she said.

Said Najmi, 74, who was evacuated today with heart disease, said, "Women are going to the sewers to fetch water, and even then they are being sniped at." He said there was "no meat, no medicine," in the camp hospital, where "many of us were gathered, on top of one another."

Meanwhile, the Lebanese Army command said the Christian commander of an air base at Riyaq, in the Bekaa Valley, was shot to death by unidentified gunmen while driving in a nearby village in Syrian-controlled territory populated largely by Shiites.

Israeli Prime Minister Shimon Peres said in an interview with Europe No. 1 radio that Israel's troop withdrawal from Lebanon will be completed Thursday, the third anniversary of its invasion, The Associated Press reported.