Israel killed a top political leader of Hamas Thursday, prompting the militant Islamic group to ditch a shaky seven-week-old cease-fire and urge its fighters to strike back at Israel.

The killing of Ismail Abu Shanab -- considered by Palestinians and independent analysts as a moderate in the militant group -- was carried out in response to a suicide bombing in Jerusalem that killed 20 people.

The collapse of the truce following Abu Shanab's death in an Israeli helicopter missile strike in Gaza could sink a U.S.-backed "road map" peace plan aimed at ending nearly three years of violence and creating a Palestinian state by 2005.

"We urge all our cells of fighters in Palestine to strike in every corner of the Jewish state," Hamas' armed wing, the Izz el-Deen al-Qassam Brigades, said in a statement.

In what Hamas called its initial response, it fired more than a dozen mortar bombs and make shift Qassam rockets at Jewish settlements in the Gaza Strip and at the town of Sderot inside Israel, causing slight damage but no casualties, witnesses said.

The White House urged Israel to work with the Palestinian Authority to crack down on the militants.

"Israel has a right to defend herself but Israel needs to take into account the effect that actions they take have on the peace process," White House spokesman Scott McClellan told reporters accompanying President Bush in Portland, Oregon, during a trip to the Pacific Northwest.

POWELL APPEALS TO ARAFAT

Secretary of State Colin Powell urged Palestinian President Yasser Arafat to use security forces to thwart attacks on Israel and warned against abandoning the road map.

"(I) call on Chairman Arafat to work with (Palestinian) Prime Minister (Mahmoud) Abbas and to make available to ... Abbas those security elements that are under his control so that they can allow progress to be made on the road map -- end terror, end this violence," Powell said at the United Nations.

"At the end of the road map is a cliff that both sides will fall off."

Powell's appeal to Arafat, whom Washington has tried for months to marginalize, was an implicit acknowledgment that he retains influence and the moderate Abbas may not have enough clout to stop attacks on Israel.

Israel decided to return to tougher military action against militants after a Hamas suicide bomber blew himself up on a Jerusalem bus Tuesday. Hamas claimed the bombing as a retribution for the killing of members of the group and said at the time it viewed the cease-fire as intact.

About 10 Israeli tanks and armored personnel carriers rolled into the town of Jenin late Thursday in a sweep for militants after a three-hour operation in the West Bank city earlier in the day, witnesses said.

Israeli tanks and troops also continued a sweep for militants in Nablus after pushing into the city Wednesday.

Abu Shanab died with two bodyguards when five missiles fired by helicopter gunships shattered his car as it drove through Gaza City, witnesses said. Fourteen passersby were wounded.

Abu Shanab was a senior figure in Hamas' political wing, and second only to its spiritual leader, Sheikh Ahmed Yassin.

He had taken part in a truce dialogue with Abbas, who is committed to coexistence with Israel. Abbas called the missile attack "an ugly crime" and thousands of Palestinians marched in rallies across the Gaza Strip to protest against the killing.

A senior Hamas spokesman told reporters the attack freed the group from its commitment to observe the unilateral truce.

(China Daily August 22, 2003)