Palestinian gunmen shot and killed one Israeli border policeman and wounded three others in violence at the start of the Israeli holiday honoring its war dead.

Israel's Army Radio said three gunmen opened fire on one of its vehicles as it patrolled late Sunday just south of the West Bank city of Hebron. An Israeli Arab was wounded in a second shooting as he stood guard at an Israeli settlement.

Israel is marking a Memorial Day holiday honoring the dead in the country's wars. The observance is followed a day later by Independence Day marking the 56th anniversary of the creation of the state of Israel.

Security forces are on a heightened state of alert for the two-day period as Palestinian militants are vowing to retaliate for Israel's assassination in recent weeks of two of the principle leaders of the Hamas militant group.

Meanwhile, there are signs that Prime Minister Ariel Sharon is backing away from threats against Yasser Arafat. Deputy Prime Minister Ehud Olmert told Israel's Army Radio that Mr. Sharon has no plans to expel or assassinate the Palestinian leader.

Mr. Olmert said the Israeli leader was merely repeating a long-standing Israeli position when he said Mr. Arafat should be eliminated. He said, The prime minister does not intend to carry out anything next week or today or tomorrow.

Last September, Israel's cabinet decided Mr. Arafat should be removed, following a pair of suicide bombings that killed 15 Israelis.

Israeli President Moshe Katsav suggested that U.S. pressure on Mr. Sharon may have caused him to back away from action. He told Israeli television that, in his words, if the United States asks us not to liquidate Yasser Arafat, I assume that the government will honor that request.

Mr. Sharon said last Friday that he had told President Bush that Israel is no longer bound by a pledge not to attack Mr. Arafat. The remarks drew a rebuke from U.S. officials, who stressed Mr. Bush's opposition to any attempt to harm the Palestinian leader.