Israel has seized effective control of more than half of the land in the West Bank during the almost 19 years it has occupied the territory, according to a critical study released today.

The study says that 567,125 acres -- 41 percent of the West Bank -- are now in the direct possession of Israelis and that on another 142,500 acres owned by Arabs, Israel has imposed prohibitions against building and other land- use restrictions that preclude independent Arab development.

Together, outright expropriation and the land-use restrictions give Israel effective control of 52 percent of the West Bank, enough territory to support up to 1 million Jewish settlers, according to the report.

The report also charged that, in addition to changing the dominant character of the West Bank from Arab-owned to Jewish-owned, Israel has used methods to gain direct control of land that raise legal questions.

The 98-page report was produced by the Jerusalem-based West Bank Data Base Project, headed by Meron Benvenisti, a professional city planner and former deputy mayor of Jerusalem and also a longtime critic of Israeli policy in the West Bank. The project is an independent research organization that monitors the growth of the Jewish presence in the West Bank and is funded by grants from the Ford and Rockefeller foundations.

The study, reportedly the most extensive made of Israeli land expropriation policies in the West Bank, charged that those policies have been designed to create a "dual system" for the benefit of Israelis, and to leave the territory's 800,000 Palestinian residents isolated in "a patchwork of hostile regions, alienated and severed" from each other.

"The Israelis, by imposing direct control over half of the West Bank, have actually created two spatially segregated regions, ethnically divided, separate and unequal," the report said.

It also said that the long Israeli occupation of the West Bank has helped to almost completely reverse the historic pattern of land ownership in what was the British Mandate of Palestine -- including what is now Israel, the West Bank and the Gaza Strip -- until the creation of Israel in 1948.

"Thirty-eight years ago, in 1947, the Jews possessed less than 10 percent of the total land of mandatory Palestine," it said, with the majority in Arab hands and the rest controlled by the British authorities. "Now, the Arabs (including the Arab citizens of Israel) are left in possession of 15 percent of that land," it said, and all the rest is in Jewish hands, either privately owned or under the control of the Israeli military government in the West Bank.

In an interview today, Benvenisti said the report, entitled "Land Alienation in the West Bank," was originally to be part of a larger study on land use and planning in the West Bank that was scaled down because of lack of funds. He said he expected critics to dispute many of his conclusions but said the findings on the extent of Israeli land seizure in the West Bank are all based on official documents and not subject to challenge.

There has been no Israeli government reaction to the study, although it was widely publicized in the Israeli press and broadcasts. In the past Israel has denied critics' charges of wrongdoing in its administration of the West Bank.

Israel has argued that the Geneva Convention's provisions regarding militarily occupied territories do not apply because Jordan's previous control of the territory had no international standing, and it has denied displacing the Arab population. It also has said that bona fide Arab owners have been fully compensated in private transactions and has emphasized that in many cases the land now being taken by Israelis is land previously seized from Jews by Arabs.

Benvenisti contends that the Jewish presence in the territory is so extensive that it precludes the possibility of a Middle East peace settlement based on a return of the West Bank to Arab sovereignty. Even today, he said in the interview, the national unity government here is continuing a process by which it formally takes possession of land that has been declared to be within the "state domain."

Benvenisti questioned the legality of many of the methods that successive Israeli governments have used to acquire land in the West Bank, which Israel captured from Jordanian control in the 1967 Middle East war. Even if those methods were technically proper under Israeli law, he argued, "If the law is to embody such concepts as natural justice, this definitely does not represent the rule of law."

The study compares the methods Israel has used to seize land in the West Bank with methods used by the British in Ireland and the French in Algeria.

In the West Bank, the methods have included the takeover of property abandoned by its owners, the "compulsory purchase" of land for public purposes and the closing of vast tracts for military use -- often, according to the study, as a prelude to creating civilian Jewish settlements in the closed areas.

The study says the most important land expropriation method used by Israel was developed in 1979 under the government of former prime minister Menachem Begin. Under provisions of a law dating back to the Ottoman Empire, which controlled Palestine before World War I, Israel declared that all West Bank territory that was not being cultivated and had not been legally registered with Jordanian authorities before 1967 was "state land," with the burden of proving otherwise left to the Arab claimants to the land.

This provision had remained dormant, however, and was not used by Britain or Jordan during their periods of control, according to Benvenisti.

Nor was it ever used by Israeli governments until 1979 when, he said, the old system of "closing" areas for military use and other such methods largely had exhausted themselves and the Begin government needed a much more sweeping tool to activate its ambitious settlement plans. The Israeli Supreme Court upheld the government when the policy was challenged.

According to the study, this method, adopted shortly after the signing of the Egyptian-Israeli peace treaty and the beginning of the "autonomy talks" on the future of the West Bank, allowed Israel in a single stroke to triple the amount of "state land" in the West Bank, to 537,500 acres.

The study estimated that 425,000 acres of this land already has been formally taken over by the Israeli government, with the remainder still to be processed through government declarations and appeals by Arab claimants that are rarely successful.

The study said that building prohibitions and other land-use restrictions have been imposed on 142,500 acres in the West Bank -- 18 percent of the land in the territory that remains in Arab hands. The restrictions are used to prevent Arab land development near Israeli military facilities and civilian Jewish settlements, according to the report.

The report also said the Geneva Convention prohibits the transfer of population to an occupied territory and that Israel, by seizing land for "military purposes" and then converting that land into civilian settlements, "is not fulfilling its obligations under the Geneva Convention but rather violating that convention" -- an interpretation Israel has repeatedly disputed in the past.

The report argued that Israeli policy in the West Bank has been designed not only to increase the Jewish presence but to divide and weaken the Arab communities there. Official Israeli master plans for the West Bank, according to the study, list as a major government objective the "fragmentation of Arab settlement blocs" in the territory.

"Land-control methods are meant to encircle the Arab areas and to penetrate them by long strips of 'prohibition-of-building areas,' " the report said. "The road network is designed to bypass Arab population centers, but also to fragment and dissect Arab settlement regions. In fact, the 'prohibition-of-building' orders force the Palestinians into rigid boxes, which prevent natural expansion."