Referring to the Israeli shelling that killed 18 Palestinians, mostly women and children, in the Gaza town of Beit Hanun on Wednesday, Palestinian UN observer Ryad Mansour said: "This is state terrorism. These are war crimes, for which the perpetrators must be held accountable under international law."
"The lawlessness and impunity of Israel must be brought to an end, and the Palestinian people must be accorded their rights, including their right to protection as a civilian population under occupation," he added.
Mansour called for "an investigation of the massacre ... and for a UN observer force to monitor (a) mutual cease-fire."
He spoke during an emergency debate of the Security Council called by Qatar, the lone Arab member of the council, on behalf of Arab UN member states. Twenty-seven speakers were scheduled to take the floor.
Qatar on Wednesday circulated a draft resolution condemning what it dubbed the Israeli "massacre" in Beit Hanun and calling for "an immediate cease-fire" between Israelis and Palestinians, the dispatch of a UN observer force and an investigation of the killings.
The draft also urged the international community, including the diplomatic Quartet -- the United States, Russia, the United Nations and the European Union -- to take immediate steps to help revive the moribund Middle East peace process.
Diplomatic sources said the draft, in its current form, was unacceptable to many council members, particularly the United States, a steadfast ally of Israel.
They added that the text was unlikely to be put to a vote before on Friday.
A Western diplomat said that the text, even if amended, was likely to face a US veto in the Security Council and that Arab countries would probably then take the issue before the 192-member General Assembly.
In his address to the council, Israel's deputy UN representative Daniel Carmon reiterated his country's "deep sorrow and regret" over the accidental killing of innocent civilians.
But he told the council that "terrorism" by the ruling Palestinian Hamas movement was to blame for the Beit Hanun incident.
"If Palestinian terror did not continue to assault Israelis, if Qassam rockets stopped sailing out of Gaza into Israel, the incident in Beit Hanun would never have happened," Carmon said. "A single decision is needed: The Palestinian Authority government must decide to stop using terrorism as a means to achieving its goals."
Speaking on behalf of the European Union, Finland's UN Ambassador Kirsti Lintonen said: "While recognising Israel's legitimate right to self-defence, we urge Israel to exercise utmost restraint and underline that action should not be disproportionate or in contradiction to international law."
"We call on Israel to end its incursion in Gaza," she added, while pressing Palestinian leaders to put an end to the firing of rockets on Israeli territory.
US Ambassador John Bolton, for his part, said his country deeply regrets the loss of Palestinian lives but supported Israel's right to defend itself and the lives of its citizens.
The council also heard a briefing from UN assistant secretary general for political affairs Angela Kane on the latest developments in Gaza.
She recalled that UN chief Kofi Annan had "reminded both sides of their obligations under international humanitarian law regarding the protection of civilians in armed conflict and reiterated his call to the Israeli government to cease its military operations in Gaza without delay."
"We hope that both Israelis and Palestinians will, in the wake of yesterday's tragedy in Beit Hanun, pause and reflect on the fact that the conflict between them will not be resolved by force, and that ways must be found to bring about negotiations," she added.
The 18 Palestinians were killed on Wednesday when Israeli shells slammed into their Gaza homes in an attack that drew world-wide condemnation and vows of renewed suicide bombings.
The deaths prompted moderate Palestinian president Mahmud Abbas to accuse Israel of destroying peace hopes and rival Palestinian factions Hamas and Fatah to call for renewed suicide attacks.

Copyright AFP (Agence France-Presse), 2006