-- Faced with violent opposition and military disobedience, Prime Minister Ariel Sharon warned Tuesday that Israel's democracy was being threatened by the "wild behavior" of a small group of settlers opposed to his plan to withdraw from the Gaza Strip this summer.

Sharon has previously criticized radicals within the settler movement, but never in such stark terms or in such an important venue. He spoke before several hundred officials of the Jewish Agency, a quasi-governmental organization that encourages Jewish migration to Israel.

Sharon delivered his speech two days after several dozen settlers scuffled with Israeli soldiers in Shirat Hayam, one of the 21 Gaza settlements scheduled for evacuation. The settlers were part of a group that has moved into a beachfront hotel in the hopes of preventing the evacuation. Israeli soldiers were razing 11 surrounding cottages when the settlers tried to block their way.

"This minority does not represent all the settlers," said Sharon, who long championed the movement to settle in lands occupied during the 1967 Middle East war. "We must remember that the call to disobedience and the attempts to disrupt the lives of Israelis endangers the existence of Israel as a Jewish and democratic nation.

"We must all, no matter our personal opinion, oppose this," he continued.

Sharon has spent enormous political capital pushing his plan to withdraw all 8,500 settlers from Gaza and another 700 from four settlements in the northern West Bank.

Some of his most ardent supporters have turned against him over the plan, known in Israel as disengagement, which he says is necessary to improve Israeli security and protect its Jewish majority from the threat of demographic trends, as the Palestinian population surges.

In leaving Gaza, Sharon is also casting off the 1.3 million Palestinians who live there. The disengagement, he said, was in part an acknowledgment that the Gaza Strip "will never be part of the State of Israel in any final agreement."

But his tone suggested a new sense of urgency as extremist settler groups stepped up a civil disobedience campaign with less than two months to go before the month-long evacuation is due to begin. Sharon's plan is opposed by a majority of Israel's settler movement, which is also divided over what tactics to use.

Blocking traffic, gluing shut the locks of government buildings and other small acts of sabotage have marked the anti-disengagement effort so far. But there are signs that those tactics are escalating. Many Gaza settlers expressed dismay over the recent arrival of new residents, for example, and asked Israeli forces to clear them out to avoid trouble during the evacuation.

Settler groups have called on Israeli soldiers to refuse orders to carry out the operation, which will involve about 40,000 troops. In the most high-profile act of defiance yet, Avi Bieber, a 19-year-old corporal in the Israeli army, refused to participate Sunday in demolishing homes in Gaza. On Tuesday, he was sentenced to 56 days in jail in a military disciplinary hearing.

It was also disclosed Tuesday that Lt. Gen. Dan Halutz, the military chief of staff, received an anonymous letter recently warning that "if your family is important to you, abstain yourself from this."