LEADERS of the Jewish settler movement in the occupied West Bank are worried by the resurgence of provocative acts by extremists in their midst. Some speculate that an underground terrorist movement may emerge out of frustration over the Army's inability to crush the Palestinian uprising. In two recent, widely publicized shows of ``settler hysteria,'' Jews ``hiking'' in the West Bank shot to death two Arab villagers and dozens of settlers mounted an ugly verbal attack on Prime Minister Yitzhak Shamir at the funeral of a slain Jew, Frederick Rosenfeld. Such incidents have set off alarms among the settler movement and led to calls to restrain extremists where possible, before they alienate a public whose support is needed to keep the aim of ``Greater Israel,'' - a nation that would include the occupied West Bank - alive.
Such efforts were complicated this week when the settlement group Gush Emunim (Bloc of the Faithful) announced of plans to take 50 hikes today in the West Bank to demonstrate that Jews in the territories should be able to walk anywhere freely.
The hikes - unlike those lately which ended in confrontation - have been approved by the military, will probably have Army escort, and are barred from entering Palestinian villages, Defense Ministry sources say.
Critics, however, such as the English-language daily, the Jerusalem Post, accuse the settlers of trying to spark confrontations with Arabs that could thwart Mr. Shamir's proposal for Palestinian elections in the occupied territories. Settlers say that initiative will lead to a Palestinian state.
Since the uprising erupted in December 1987, settlers have complained the Army has not done enough to protect them from Arab stone- and firebomb-throwers. They condemn the government for failing to take harsher measures to crush the unrest.
David Bedein, a publicist who promotes Jewish settlement in the West Bank and Gaza Strip, acknowledged growing concern about fanatics among a population that has been armed with automatic weapons by the military for self-defense.
Describing ``a bunch of macho guys'' as ruining the settlers' image, Mr. Bedein said the approximately 80,000 Jews living in the territories ``are going to have to do a heck of a lot to regain the sympathy'' of the Israeli public.
In the first visible efforts during the intifadah (uprising) by settlement leaders to calm the population, three prominent West Bank rabbis in the past week called for changes at ``Joseph's Tomb'' yeshiva, or school of Torah study, in the Arab city of Nablus.
Students there were involved in a rampage on the village of Kifl Harith last month in which a 13-year-old girl was shot dead, two other villagers wounded, fields and property set on fire, and windows and cars smashed. The yeshiva rabbi condoned the attack, saying Jewish blood differed from Gentile blood.
Members of Gush Emunim also have held meetings and placed notices in local newspapers, urging residents fed up with Arab attacks and angered by the slaying of Rosenfeld last week to ``stay calm and act responsibly,'' says group spokesman Noam Arnon.
``The idea of loss of control is not exact,'' said Rabbi Menachem Fruman, of the settlement of Tekoa, who called for a more responsible body at the Nablus yeshiva. ``We have no direct control on every yeshiva or every settler. We're not an army. It's our responsibility to calm the public because after one and half years of the intifadah, some people can move to extremist ways.''
There also is mounting concern among some settler leaders and authorities that extremists may form a terrorist group similar to one broken up by police in 1984 after four years of violence against Arabs - including killing Arab students, grenade attacks, and plotting to destroy a sacred Muslim site, the Dome of the Rock, in Jerusalem.
``I'm afraid there will be a new underground because there are fanatic people who don't believe in the IDF [Israel Defense Forces] or the government anymore,'' said Rabbi Yehuda Amital, of the Gush Etzion settlement bloc south of Jerusalem. ``There are people who believe their job is to save the Jewish people. You don't need a lot of them. Ten is enough.''
Concern grew last week when police linked a settler suspected of shooting two Arabs near Tel Aviv to the killing of a Palestinian in Jerusalem earlier this year and announced they were looking into the possibility the suspect worked with others.
Police also arrested settler Meir Berg in the murder of an Arab in the village of Karawat Bani Zeid last Friday during a hike of 11 Jews. Another settler is suspected of wounding a second villager.
Despite the violence - in which the Jews entered the village without Army approval - Gush Emunim announced the 50 hikes to ``strengthen the right of any human being to hike and to tour where he wants without interruption,'' Mr. Arnon said. ``If the [Arabs] attack the hikes, the hikers will defend themselves.''
Meanwhile, Bedein and other settlers say exasperation over the Army's apparent lack of concern for their safety has created a breeding ground for lawlessness and fanaticism.
``The underground of the 1980s was a result of 12 Jews being murdered and the complete lackadaisical response on the part of the Defense Ministry,'' Bedein says.
``What we said a year ago is that we might lose control if the situation goes on. It has become true, unfortunately,'' Arnon says.