Relatives and friends mourned Hassan  Abu Ida, 54, who died on Saturday  from wounds he suffered in an Israeli  strike in Gaza on June 13.

JERUSALEM, — Israeli undercover troops operating in the volatile West Bank city of Hebron shot and killed a senior leader of the Hamas movement who was suspected of organizing several recent suicide bombings, Israeli security sources and Palestinian witnesses said this morning. The Israeli operation on Saturday night came one day after Secretary of State Colin L. Powell met with Israeli and Palestinian leaders in an attempt to conclude a cease-fire agreement that had been under negotiation for weeks. President Bush attended a Middle East summit meeting on June 4 to begin talks on the peace plan, but that effort too was followed within days by renewed outbursts of violence.  The Israeli soldiers were trying to arrest the Hamas man, Abdullah Qawasmeh, when he was shot, according to an Israeli official. But Palestinian witnesses and journalists in Hebron said the troops made no attempt to detain Mr. Qawasmeh.

They said the soldiers opened fire as he reached the street around 10 p.m. Saturday night after leaving evening prayers at the Al Ansar mosque in the center of Hebron. Israeli troops then cordoned off the area around the mosque, Palestinians said.

While the circumstances of the shooting were in dispute, such Israeli operations are a central issue in the current efforts to negotiate a cease-fire in the Middle East.

Israel says it will continue to track down Palestinian militants for arrest and will also kill those suspected of planning or carrying out violence. Israel says it will only stop the practices when Palestinian security forces begin to act against militant groups.

Israel's foreign minister, Silvan Shalom, said Saturday that no truce would be reached unless the Palestinians clamped down on the organizations responsible for suicide bombings and shooting attacks.

The Palestinian prime minister, Mahmoud Abbas, "has not made the strategic decision yet on dismantling terrorist infrastructure," Mr. Shalom said on Israel radio. "If we do not stand our ground on this issue, it will be impossible to reach a breakthrough."

However, Palestinians are demanding that Israel halt the killings as part of cease-fire agreement. A Palestinian Authority official, who requested anonymity, called the shooting of Mr. Qawasmeh a major provocation at a time when the Palestinian leadership was trying to persuade Hamas to suspend attacks. Mr. Qawasmeh's death was sure to draw an angry response from Hamas, which has so far refused to accept the truce proposal.

Israeli sources said Mr. Qawasmeh was linked to several recent suicide bombings, including the June 11 attack on a Jerusalem bus that killed 17 civilians.

Mr. Qawasmeh was known as the Hamas leader in Hebron who recruited suicide bombers, according to Palestinian sources in the city.

The Qaswasmehs are a large clan in Hebron, a city south of Jerusalem, and several members have been involved in recent attacks carried out by Hamas. Fuad Qawasmeh, 21, blew himself up in Hebron on May 17, killing a Jewish settler and his pregnant wife. The relationship, if any, between Abdullah Qawasmeh and Fuad Qawasmeh was not immediately known.

The Israeli operation came a day after Mr. Powell met Mr. Abbas and Prime Minister Ariel Sharon of Israel to push for a cease-fire, but was unable to bridge the differences.

The Israeli-Palestinian talks are stalled over a plan for Israel to remove troops from the Gaza Strip, and for the Palestinian security forces to move in and prevent attacks against Israel.

The Palestinians want Israeli forces out of all Palestinian areas in Gaza, while the Israelis want to maintain checkpoints along Salahuddin Road, which runs the length of Gaza from north to south. The Palestinians are also demanding the release of Palestinian prisoners, in addition to an end to targeted killings.

Mr. Abbas, who met Mr. Powell in the West Bank town of Jericho on Friday, was back in Gaza Saturday as part of his ongoing effort to work out a truce.