The World Zionist Organization today proposed increasing the Jewish population of the West Bank by 600 percent in the next four years, by building 18 to 20 new settlements and moving 100,000 more Jews into the occupied territory.

The proposal, part of a master plan to increase the Jewish population in the West Bank from its current 20,000 to 1 million within 30 years, will be presented to the government for approval within a few weeks, according to Matityahu Drobles, cochairman of the organization's settlement division.

Zeev Ben-Yosef, spokesman of the settlement division, noted that so far the government has approved every settlement proposal submitted by the World Zionist Organization, a quasigovernmental agency that shares responsibility for Jewish development of the occupied territories with a ministerial committee on settlements and the Ministry of Agriculture.

The plan appears at odds with a statement by Prime Minister Menachem Begin on May 27, 1980, that Israel would build "only 10 more settlements , then it's finished. This is what we need for our security." At that time, there were 44 Jewish settlements in the predominantly Arab West Bank, and now there are 85 completed or under construction.

The World Zionist Organization's proposal also appears to contradict a Sept. 11 statement by Agriculture Minister Simcha Ehrlich that the government intends to build a maximum of four new settlements in the West Bank.

When asked about the new expansion plans, Begin's press secretary, Uri Porat, said today, "I don't know if these are new settlements or old plans. The government hasn't received anything on it yet."

The plan calls for increasing to 50,000 the population of existing settlements that have been designated for expansion into urban development, including Ariel and Elkana close to the pre-1967 Israeli border, and Karnei Shomron, west of the Arab city of Nablus.

Much of the remaining 50,000 would be in 10 new settlements to be developed on the western slopes of the Samarian hills and in a security belt around Jerusalem. Other new settlements would be scattered throughout the West Bank, bringing the total to between 103 and 105.

The World Zionist Organization sought to minimize the impact of the new construction aspects of the expansion plan, emphasizing that it is more concerned that the settlement structure already established in the West Bank be sufficient to accomodate three times its current 20,000 population.

"The new settlements we are proposing are not important. What is important is that we have fixed some facts on the ground in Judea and Samaria and now we have to make them permanent by increasing the population to 100,000," Ben-Yosef said.

Zionist organization officials dismissed suggestions that a decline in Jewish immigration to Israel and growing reluctance of Israelis to move to the inhospitable and arid Samarian hills would make it difficult to recruit 100,000 settlers.

"The demand to settle is very, very big. We now have thousands of people who want to settle in Judea and Samaria. I have on my desk letters from people who are willing to pay to build their own homes," Ben-Yosef said. The government heavily subsidizes housing in settlements.

The organization said establishment and expansion of settlements is designed to attract a third of the anticipated population growth in the coastal plain near Tel Aviv. It is said most of the settlers will be required to commute to jobs in Israel proper, with an expected 40 percent being locally employed, mostly in light industry, in the settlements.

Officials of the organization refused to estimate the cost of the settlement program, part of which is borne by contributions by world Jewry and part by grants from ministries such as housing and agriculture. In the past, the World Zionist Organization has estimated that the annual cost of new and expanded settlements is about $600 million. Direct and indirect investment by the government has been estimated at about $350 million.