In the wake of the expulsion of three prominent West Bank figures after the ambush killing of six Jewish settlers Friday, the militant Palestinian leadership has been driven undergound, where it eventually could prove an even greater irritant to the Israeli occupation authorities.

That conclusion emerged today as the unofficial leadership of the 950,000 Palestinians in the West Bank, once shred with Hebron Mayor Fahd Kawasme and Halhoul Mayor Mohammed Milhem, was left mostly in the hands of the radical mayors of Nablus and Ramallah, Bassam Shaka and Karim Khalaf.

Kawasme and Milhem, along with Sheik Rajab Tamimi, Hebron's religious leader, were expelled to Lebanon hours after Arab gunmen opened fire on a group of settlers and religious students in Hebron. Five Israelis were killed on the spot and 17 others were wounded. One of the wounded died last night.

In the West Bank today, there were scattered demonstrations that were quickly broken up by security forces. Schools were closed in Ramallah and EL Biera, and a curfew remained in effect in Hebron and in the village of Anabta, where an Arab youth was shot to death last week in a scuffle with an Army captain.

Although they were accused by the military government of inciting violence by making nationalistic public statements, Kawasme and Milhem in recent months had been relatively modrate voices in the West Bank's complex political structure.

Often at the expense of biting criticism by some of their colleagues on the 21-member, sub rosa Palestinian National Guidance Council, they advocated establishing a dialogue with members of Israel's growing peace movement and other "good Israelis," with the aim of reaching a political solution to the Palestinian problem.

The Guidance Council was formed after the signing of the Camp David peace accords as a means to promote West Bank nationalism and coordinate opposition to the limited autonomy plan proposed for the occupied territory. It had been a vehicle for the radicals' bid for leadership supremacy in the West Bank, and Shaka and Khalaf -- although outnumbered by moderates -- had controlled most of the group's major decisions.

Often, those decisions followed policy more closely attuned to the rejectionist wing of the Palestine Liberation Organization, including George Habash's Popular Front for the Liberation of Palestine, than to the Fatah, the main branch of PLO.

It is a measure of the constantly changing face of West Bank politics that the Fatah-associated West Bank leaders are now considered moderates by many Israelis, while the terms "radicals" and "extremists" are reserved for those with ties to Habash or the Iraqi-linked Arab Liberation Front.

In a recent conservation, Kawasme and Milhem heatedly rejected the notion they are close to Habash. When teased about the pratice of Israeli television using Habash's name with his own photograph captions, Kawasme snapped to a reporter, " If I'm Habash, you're Iraqi!"

Kawasme was elected Hebron mayor in 1976 when PLO supporters swept the West Bank balloting, but he had long been associated with the moderate wing of Palestinian leadership, having previously worked for the Israeli occupation government as an agricultural engineer.

Kawasme attracted criticism from the radical mayors for his frequent meetings with the Hebron military governor. But during his stewardship, the city prospered economically and Kawasme became known as one of the most effective city managers in the West Bank.

Several months ago, Kawasme appeared to change, which has been widely attributed to the Israeli Cabinet's decision to settle Jews in the center of exclusively Arab Hebron. His criticism of Israel became more caustic, until at a March 24 rally he predicted "the Zionist empire will fall, just as the British empire and the Nazi empire fell before." That comment led to his deportation.

Milhelm, 50, almost boyish looking, was also elected in 1976 by Halhoul voters to the post his brother, Mustapha, held before he was expelled for seditious statements.

A former high school English teacher who once worked for the Aramco oil producing conglomerate in Saudi Arabia, Mohammed Milhelm maintained close ties to Shaka and Khalaf, but he was generally considered more moderate. He was a member of the National Front, a PLO-lined eight-member committee that was banned by Israel.

While he openly identified with the PLO, as all the West Bank mayors do, Milhelm often met with liberal Jewish groups and repeated his willingness to accept the existence of the Jewish state alongside an independent Palestinian state.

His expulsion has been condemned by many libral Israelis, who view it as creating a vacuum in responsible Palestinian leadership.

Shaka, whom the Israeli military government attempted to deport last year for inflamatory statements, and Khalaf, along with most members of the Guidance Council, were virtually incommunicado today following the crackdown in the West Bank by security forces.

Both of them, along with El Biera Mayor Ibrahim Tawil, also a member of the Guidance Council, have been warned under the threat of deportation not to speak to foreign journalists or hold any public meetings, according to informed West Bank sources.

Strict censorship is imposed on Arabic newspapers published in the West Bank and East Jerusalem, some of which are controlled by Guidance Council members.

All of the mayors have been warned they will be held personally responsible and face expulsion if there are any anti-Israeli demonstrations in their towns.

But members of the Guidance Council -- which in addition to mayors includes communist leaders, labor union officials, heads of charitable groups and newspaper publishers -- said that the council will continue to organize occupation resistance underground.

They said the council probably will reorganize into smaller local cells to coodinate poltical activities without attracting the attention of the Israeli security authorities, and that in time they will become effective again.