The bulldozer came to the home of Hussein Mahmoud Abu Ubuid around noon on June 28. It came along the narrow road that runs between the sand dunes and the sea, then churned over the sand until it stood before Abu Ubuid's ramshackle house on the edge of this Palestinian refugee camp.

The bulldozer was accompanied by other vehicles and, in Abu Ubuid's recollection, about 20 Israeli soldiers, one of whom issued the order: The family, totaling 19 people, had 30 minutes to remove their belongings from the house before the bulldozer began to demolish it.

Abu Ubuid, at 38 already a grandfather, was told his house was illegal, built without the necessary permit from Israeli authorities.

He was not the only one to lose his home this summer in the Gaza Strip, captured by Israel in the 1967 war and under Israeli military occupation since then. According to officials of the U.N. Relief and Works Agency, which provides services in this and seven other refugee camps in Gaza, about 35 families numbering more than 150 people have lost their homes to Israeli bulldozers during the past six weeks. More demolitions are expected, U.N. officials say.

A spokesman for the Israeli Defense Ministry in Tel Aviv said the "only reason" for the demolitions was that the houses were built without proper permits. "The same steps are taken in Israel in similar cases," he said, adding that "if someone builds without permission they will have to take it down."

But Abu Ubuid said members of his family have lived on the same property on the northern edge of Beach Camp since the mid-1960s. Except for five years ago, when the Israelis tore down an addition to the house they said extended beyond the limits of the refugee camp, the family has not been bothered by authorities or told they needed a permit, he said.

According to Peter Hawkins, director of UNRWA operations in Gaza, the Israelis inexplicably announced this year they would begin to enforce an old law requiring permits for building. He said the law dates from the 1960s when the Gaza Strip was administered by Egypt. In other cases, he said, Israeli authorities have maintained that some of the houses were built outside the legal boundaries of the camp.

Hawkins said he has not challenged the legal right of Israeli authorities to enforce the law, even retroactively, but has argued against the demolitions, so far to no avail, on humanitarian grounds.

"We have no surplus accommodations here, no alternative housing for these people," he said.

The demolitions, although on a relatively small scale so far, have exacerbated the always acute housing shortage in the Gaza Strip, one of the world's most densely populated spots. A narrow strip of land six miles wide at its maximum, the territory runs for 25 miles along the Mediterranean coast to the border with Egypt. Within its confines live about 500,000 Palestinian Arabs, more than 300,000 of them registered with UNWRA as refugees from the 1948 creation of the state of Israel and the war that followed it, or their descendants.

Before 1967, Israel considered Gaza a major security problem. But a harsh antiterrorism campaign directed by then general Ariel Sharon in the early 1970s largely pacified the territory. Today Gaza is the scene of far fewer disturbances, and receives far less public attention, than the West Bank, also captured by Israel in 1967.

But for many Gaza residents, living conditions, especially in the refugee camps, have remained primitive over the years. Unemployment is a major problem and a high birth rate has meant cramming more and more people into the camps, giving them the unmistakable, chaotic look of refugee centers.

"The camps," Hawkins said, "are bursting at the seams."

In the early 1970s, Israel began a program of government housing centers in Gaza, encouraging refugees to move from the camps. According to Hawkins, about 30,000 refugees have made the move, but to do so they must come up with the money to purchase the land and construct the housing, as well as arrange to demolish their old homes in the camps.

Israel's long-term goal is to do away with the camps, just as immediately after last summer's invasion of Lebanon Israeli officials said they hoped to see the elimination of the Palestinian refugee camps in southern Lebanon. Those camps are now rapidly being rebuilt. But many Palestinians, viewing the camps as ugly reminders of what they consider the injustice that was done to them in 1948--when the state of Israel was created, using much of the land inhabited by Arabs--resist the idea of being absorbed into Israeli government housing centers.

Hawkins and other U.N. officials said there is fear in Gaza that this summer's demolitions may be an attempt to accelerate the move of refugees to the housing centers. They also said Israeli officials are considering constructing a "security road" along the coast in Gaza, a project they said would require large-scale demolitions in Beach Camp and another camp along the sea coast farther south.

But the more immediate problem is finding housing for those who have already lost their homes this summer. U.N. officials said discussions of alternative housing have been held between refugees and Israeli authorities in the Gaza civil administration, but that so far nothing appears to have come from them.

Some of the newly homeless refugees have moved in with friends or relatives. Others, such as Abu Ubuid and his family, have stayed put, surrounded by the rubble left by the bulldozer.

Two rooms of what was once a 13-room house were left standing on the property and now provide shelter for the women and children of the family, although there is no electricity or cooking or toilet facilities. The men sleep outside, and during the day sit beneath a blanket covering that shields them from the sun. Nearby a pile of rubble is littered with some of their personal belongings--a briefcase, an old record player, a mattress, a hair dryer, kerosene lamps.

The site is on the edge of the camp. Beyond it there is only open sand, a road that runs north and in the distance a grove of trees.

In addition to the house, Abu Ubuid said he lost his small shop where he rebuilt used electric motors. Several of his neighbors, including one of his brothers, also lost their homes in the demolitions which, according to U.N. records, took place intermittently between June 28 and July 14.

A week before the bulldozer arrived, Abu Ubuid recalled to the amusement of listening relatives and friends, he had been thinking of building an addition to the house because the family continues to grow.