Israel threatened Sunday to invade Gaza if Palestinian leader Mahmoud Abbas (search) does not control militants who have stepped up rocket and mortar attacks ahead of Israel's planned pullout from the coastal strip next month.

Abbas pledged to do his utmost to stop the barrages but warned that an invasion of Gaza would "sabotage everything."

Prime Minister Ariel Sharon (search) said all restraints are off and thousands of Israeli troops have massed along the Gaza border. The sudden escalation is the most serious threat yet to a 5-month-old truce that had drastically reduced Palestinian-Israeli violence after more than four years of bloodshed.

More than 100 rockets and mortars have rained down on Gaza settlements and Israeli villages just outside the territory in the last four days. Hamas (search) leaders say they are retaliating for Israeli violations of the truce.

But one leader said the main reason for the barrage was to show that Israeli settlers were fleeing Gaza under fire rather than in a planned evacuation.

In violence Sunday, Israeli soldiers killed a Hamas leader and Palestinian infiltrator, and the air force fired on a car in northern Gaza, wounding a bystander. The military said it targeted militants on their way to firing rockets, but missed.

Also, two Israelis were wounded seriously in a Palestinian mortar strike on a Gaza settlement.
Soldiers and tanks were poised to cross the Gaza border fence. Large-scale raids often have followed rocket and mortar barrages but not since the truce took effect Feb. 8.

Sharon told his ministers at the start of a weekly Cabinet meeting: "I spoke to the heads of the defense establishment ... and informed them that there are to be no restraints on our operations."

Defense Minister Shaul Mofaz told the meeting Israel would launch a "massive, prolonged and intricate" military strike if the Palestinian Authority does not stop the attacks.

Despite the tough talk, there were signs both sides want to maintain the truce. Abbas publicly called on militant groups like Hamas and Islamic Jihad to stop their attacks. Israeli officials said they are reluctant to launch a full-scale military strike for fear of being bogged down in Gaza before the evacuation.

"We are going to do our utmost to stop these rockets," Abbas told a news conference in Gaza. "I cannot promise how much time it will take me."

He said the United States warned him of Israel's intention to invade Gaza.

"If this happens, this will sabotage everything," he said.

The Palestinian leader blamed Israel for the tension.

"Israel does not want peace or security, but we don't want to be dragged to their playground," he said. "Maybe they are looking for an excuse to delay the withdrawal."

Egyptian mediators were meeting Sunday with Hamas in an attempt to reconstitute the truce, and Secretary of State Condoleezza Rice was planning a quick trip to the region to try to salvage the cease-fire.

After meeting the Egyptians, Hamas official Said Siyam said differences among Palestinians can be resolved peacefully. "The internal conflict has passed, and all issues within the Palestinian internal society can be solved through dialogue," he said, repeating the Hamas position that it is committed to the truce but has the right to retaliate for Israeli violations.

Another confrontation was developing on a separate front. Police refused to give a permit to settlers and their backers for a mass march toward Gaza on Monday. Settler leaders say tens of thousands of people are to converge on Gaza to try to block the pullout.

Police and settlers negotiated through the day, but the talks broke down when settlers refused to declare a time when the protest would end.

Defiant settler leaders said they plan to go ahead with the march, which could trigger violent clashes. There have been scuffles at the main crossing point into Gush Katif, the main bloc of settlements, every day since Israel declared Gaza off limits to nonresidents last week to prevent thousands from reinforcing the 9,000 settlers already living there.

Many of them are planning to resist the removal of all 21 settlements from the territory.

The planned evacuation also has touched off dissidence within army ranks. The army chief ordered a 40-member platoon of Orthodox Jewish soldiers disbanded Sunday after nine soldiers disobeyed orders to stop demonstrators from entering Gaza, the military said. Many Orthodox Jews reject the pullout because they consider Gaza part of the biblical Promised Land.

Palestinian police, meanwhile, began removing Hamas, Islamic Jihad and Fatah flags from the streets of Gaza early Sunday, leaving only the Palestinian national flag. On Saturday, Abbas said he would brook no challenges to his government's authority, and he called on militants to stop their attacks.

Rockets and mortar rounds continued hitting Israeli targets Sunday. Two Israelis were wounded seriously by a mortar that landed on a house in the Gaza settlement of Neve Dekalim.

An Israeli sniper shot and killed a senior Hamas field commander in a targeted strike earlier in the day after another mortar round hit the same community, the army and Hamas officials said.

Hamas, which opposes the existence of Israel and has killed hundreds of Israelis, claimed responsibility for both attacks.