JERUSALEM – Prime Minister Sharon opened a stormy debate in Parliament yesterday with a passionate appeal to lawmakers to support his Gaza withdrawal plan – which has divided the country and weakened his government – as the only way to secure Israel’s future.

The withdrawal would mark the first time Israel has pulled down Jewish settlements in the West Bank or Gaza, and Mr. Sharon is hoping a decisive victory in a parliamentary vote scheduled for today will blunt calls for a national referendum on the plan.

“This is a fateful moment for Israel. We are dealing with a difficult decision that has few parallels,” he said in a speech repeatedly interrupted by heckling from hard-line opponents.

The two-day debate in the Knesset is the climax of a months-long confrontation over the “unilateral disengagement” plan, which Mr. Sharon has pushed despite strong opposition from much of his Likud Party and the threat that it could destroy his coalition government. As the debate began, violence flared in Gaza, with Israeli troops killing 15 Palestinian Arabs and wounding 91 others in a raid on the Khan Younis refugee camp to halt Palestinian Arab mortar fire at nearby settlements. Two Israeli soldiers were wounded.

Violence in Gaza has increased in recent months, with Palestinian Arab terrorists trying to prove they are forcing Israel out, and Israel seeking to crush the terrorists to show it is not withdrawing under fire.

Mr. Sharon says his plan to leave Gaza and pull down four small West Bank settlements is vital to ending four years of devastating violence in the region. Jewish settlers accuse Mr. Sharon of caving in to Palestinian Arab violence and fear the withdrawal will be the first step in a larger pullback.

Palestinian Arabs view the plan with skepticism and worry that Mr. Sharon hopes to use the limited withdrawal to mute international criticism of Israel and strengthen its hold over large parts of the West Bank and East Jerusalem, lands the Palestinian Arabs claim for a state.

The program, which will uproot 8,800 settlers, is a sharp reversal for the premier, who was once the settlers’ top patron in the government. Mr. Sharon said supporting the withdrawal was the most difficult decision of his long career.

“I know the significance of the Knesset’s decision for thousands of Israelis who have lived for many years in the Gaza Strip, who were sent there in the name of Israeli governments, and built their homes there. Who planted flowers and trees, and brought up their children, who have never known another home,” he said. “I know this well. I sent many.”

Mr. Sharon said his plan was not intended to replace negotiations with the Palestinian Arabs in the long run.

“It is a necessary step during a period in which negotiations are not possible. All is open when terror – this murderous terror – stops.”

The plan has sharply divided Mr. Sharon’s Likud Party, with nearly half the 40 Likud lawmakers saying they will vote against it, forcing Mr. Sharon to rely on the support of dovish opposition parties. Mr. Sharon is expected to win today’s vote, but will need a solid margin of victory to silence opponents’ demand for a national referendum.

Mr. Sharon opposes a referendum, which would take months to prepare, as a stalling tactic and said it would only increase the divisions and the hatred on both sides. However, several Cabinet members, including the finance minister, Benjamin Netanyahu, have called for a national vote.

Press reports say Mr. Sharon should get at least 65 votes – and possibly as many as 70 – in the 120-member Knesset, with fewer than 48 lawmakers voting against the plan. The withdrawal plan has stirred passions on both sides.

Thousands of supporters demonstrated outside the Knesset last night, singing songs, waving Israeli flags, and holding signs reading “leaving settlements – a choice for life” and “leave Gaza immediately.” Opponents plan a major demonstration of their own before the vote today.

Also yesterday, Israel agreed to let Yasser Arafat leave his Ramallah compound for the first time in 2 1/2 years for medical treatment in the West Bank city, raising concerns the Palestinian Arab leader is seriously ill. The Defense Ministry said it made the decision after a request from Palestinian Arab officials. But Palestinian spokesman Saeb Erekat denied the Palestinian Arabs asked for such permission and said Mr. Arafat will not take up the offer.

The 75-year-old Mr. Arafat has been suffering from the flu, but is recovering, Palestinian Arab officials said.

The Israeli press has speculated that Mr. Arafat may be far more ill than has been disclosed and may actually have cancer. Mr. Arafat’s health became the subject of intense speculation after Tunisian and Egyptian doctors were flown in to examine him in recent weeks.