The settlements are viewed by much of the world as illegal because they are built on land taken in war, and as an obstacle to peace and the establishment of a Palestinian state.

Over nearly four decades they have grown, with many of the enclaves looking like ordinary suburbs. There are now 240,000 Jews living among 2.5 million Palestinians in the West Bank and another 200,000 Jews living in areas of Jerusalem also conquered in 1967.

For each of the last five years, the population of the settlements has grown by nearly 5 percent, twice the rate of the previous average growth, according to Peace Now, a group that opposes the settlements and closely tracks them. Kiryat Arba, the Jewish settlement less than a mile northeast of Hebron, has more than doubled in the last two decades, to 7,000 residents today. Hebron itself, considered to have some of the most uncompromising of the settlers, has some 700 Jews.

Settlers in Hebron say they bought their new building legally, but Defense Minister Amir Peretz has said their takeover is illegal because they did not get permission from security forces and the settlers should be evacuated. He was overruled by the attorney general, who gave the settlers two weeks to make their case to a civil court.

Mr. Olmert has said he wants to avoid the kinds of emotional confrontations that marked the Gaza evacuation so it is unlikely he will remove the settlers before all legal avenues are exhausted.

Supporters and opponents say the outcome of the building in Hebron will show how much the government is willing to confront the settlers in what the fiercest critics say amounts to a new settlement, with close to 100 residents already.

The back of the building abuts an old Arab cemetery, on a small road used frequently by Palestinian residents. The settlers say the building is the best spot they could find.