Palestinian Prime Minister Mahmoud Abbas (search) canceled a visit Wednesday to this town in northern Gaza after Israeli tanks and bulldozers once again rumbled in to try to destroy areas used by Palestinian militants.

The town had been the scene of a rare demonstration Tuesday, with hundreds of angry Palestinian residents burning tires and blocking roads to protest against Palestinian militants, whose rocket attacks against the nearby Israeli town of Sderot sparked an earlier Israeli invasion.

Abbas was scheduled to tour Beit Hanoun (search) on Wednesday to survey damage from a five-day Israeli occupation aimed at deterring militants from firing off primitive Qassam rockets (search).

The Israeli troops demolished 15 houses, uprooted thousands of trees and damaged the water and sewage systems, witnesses said. Soldiers pulled back to the town's outskirts Tuesday but continued to hold territory inside the Gaza.

Abbas, also known as Abu Mazen, canceled his visit for security reasons, and later called on Israel to "cease its escalations and invasions of Palestinian areas, because these actions only feed into the cycle of violence and deepen the hatred between the two peoples."

Also Wednesday, Israeli troops found and destroyed an explosives laboratory hidden in a tunnel in the West Bank city of Nablus and demolished the house of a militant involved in a suicide bombing in January, the army said.

Meanwhile, the Chinese envoy to the Middle East met Wednesday with Yasser Arafat, despite Israel's threats to boycott officials who meet with the veteran Palestinian leader.

"The aim is to push both sides, the Israelis and Palestinians, forward with the peace process," said Wang Shijie, China's Middle East envoy.

Israeli Foreign Minister Silvan Shalom said Wednesday that if Abbas "does not do what is needed" to end a string of terror attacks, "he will find himself in a short time ending up like Arafat."

Arafat, whom Israel is trying to sideline because of his alleged links to terror, has been holed up in his compound in the West Bank city of Ramallah for more than a year.

The Israeli action against Beit Hanoun came after a wave of Palestinian suicide attacks that killed 12 people in addition to the bombers.

On Wednesday, 15 bulldozers rumbled back into the industrial area of Beit Hanoun "and started a new wave of destruction," said Sofian Abu Zaida, chairman of the Palestinian liaison committee with Israel.

The army said troops had never withdrawn and that operations in Beit Hanoun were ongoing.

Abbas has said he will stop militants from carrying out attacks against Israel -- required in Phase I of the so-called "road map" for peace -- but has insisted Israel honor its initial commitments as well, including freezing settlements and stopping army operations in Palestinians cities and villages.

As troops rolled through Gaza on Wednesday, soldiers searching a house in the West Bank city of Nablus found and destroyed an explosives laboratory hidden in a tunnel, the army said. Troops found six explosive belts, 55 pounds of explosives and other chemicals in the tunnel.

The army also destroyed the Nablus house of an Al-Aqsa Martyrs' Brigade militant who carried out a suicide attack in Tel Aviv in January. Palestinian witnesses said eight families were left homeless by the demolitions. A house belonging to a second militant also was destroyed Wednesday in Bethlehem, the army said.

In a telephone call with President Bush on Tuesday -- the first since Abbas took office April 30 -- the prime minister "stressed the importance of Israel's implementing the road map, freezing settlements and stopping their attacks on Palestinians cities and villages," said Palestinian Information Minister Nabil Amr.

The road map is a three-stage, three-year plan that starts with an end to 31 months of violence and leads to creation of a Palestinian state.

Israeli Prime Minister Ariel Sharon has posed 15 reservations to the plan, most of them about security, and was to discuss them in talks with Bush originally set for Tuesday in Washington. Sharon postponed the visit after suicide bombers carried out five attacks on Israel in less than 48 hours. A new date has not been announced.

"Arafat is not letting Abu Mazen succeed," Shalom, the foreign minister, told reporters after a briefing at the Knesset. But Shalom added that Abbas "cannot hide for a long time under the excuse that Arafat is bothering him and he cannot carry out these actions. Abu Mazen's fate is in his own hands. If he does not do what is needed -- ending violence and incitement -- he will find himself in a short time ending up like Arafat."

Arafat named Abbas as prime minister only after giving in to intense international pressure, and critics say he has been trying to undermine him.