About 30 memebers of three Palestinian families have been living outdoors for three weeks after Israeli Army troops sealed up the doors and windows of their houses with cinder blocks as collective punishment after one son from each family was arrested on security charges.

Military authorities said the action was taken to set an example and warn other Arabs on the Israeli-occupied West Bank that families will be held accountable for their children.

Capt. Ishai Cohen, spokesman for the military governor's office, said "In the Arab society there is a strong connection between fathers and sons. It is hard to believe after acts like these that the families did not know what their sons were doing."

The three teen-aged youths have been charged with throwing a Molotov cocktail at an empty tourist bus and throwing rocks at the car of the local military governor.

The families denied that their sons, who are in jail, were involved in the incident. They said the youths were rounded up along with 200 other students at their school and were held on suspicion.

Army security forces arrived at each of the homes late at night on May 26 with a concrete mixer and a truckload of cinder blocks and gave the families two hours to remove their belongings, the families said. Then, soldiers sealed up all entrances and windows and warned the occupants that the houses would be demolished if they attempted to reenter them.

Last month, the government moved two other Arab families from their homes on the West Bank to an abandoned refugee camp in the Judean desert. Sons in each family had been accused of throwing rocks or gasoline bombs at military vehicles, but public pressures forced authorities to allow the families to return home.

Blowing up houses or sealing them has been a common practice since Israel occupied the West Bank 13 years ago, but it has been generally restricted to the most serious of security offenses, such as participation in terrorist actions or conspiracy in planned bombings of public places in Israel.

Nablus Deputy Mayor Zafir Masri complained it is part of a new hardline policy in the West Bank adopted after the May 2 Arab ambush in Hebron, in which six Israeli settlers were killed. Masri is sitting as acting mayor for Bassam Shaka, who lost both legs in a car bombing attack widely assumed to have been in vengeance for the Hebron ambush.

Felicia Langer, an Israeli lawyer, has appealed to Israel's Supreme Court to order the house sealings stopped contending they are excessive punishment in violation of the Geneva convention governing the conduct of occupying forces.

Masri said, "To punish a whole family for the conduct of one son is really unjustifiable. Let them produce evidence against the son, but what does that have to do with a mother and her small children."

The families have a total 23 children, ranging in age from two years upward, and include elderly relatives, all living outdoors under makeshift canvas coverings. One of the families vowed today to go on a hunger strike if they are not allowed to reenter their homes.

Zuhair Hijazi, a truck driver whose 16-year-old son, Munir, is in jail, showed insect bites covering the arms of his two-year-old daughter and complained every member of his family is suffering from living outdoors.