UNITED NATIONS, Dec 17: A top UN official said on Thursday that "there exists, once again, a "window of opportunity' to revitalize" the peace process between Israel and the Palestinians.

Briefing the UN Security Council on the situation in the Middle East the head of the United Nations Political Affairs office, Kieran Prendergast, said "both parties seem to have realized the potential for change inherent in the present situation," citing the smooth Palestinian transition after the death of President Yasser Arafat, the scaling back of Israeli military activity and the "critically important" dramatic drop in the Palestinian public's support for terrorism.

"There exists at present a real opportunity to implement the roadmap's provisions and to make a huge leap forward towards a settlement of the conflict," he added in reference to plan calling for parallel and reciprocal steps by both sides leading to two states living in peace by the end of 2005.

"But", he cautioned, "much work remains to be done if potential is to become achievement. We should make clear that we expect both Israel and the Palestinians to seize the moment to act constructively, and to work within the frame work of the roadmap."

Mr Prendergast had hailed the smooth preparations to elect a new Palestinian president as well as Israel's role in contributing "meaningfully to enabling a positive transition period" by resuming security cooperation and taking other constructive measures.

"With the emergence of a more positive atmosphere, support among the Palestinian public for violent acts and terror against Israelis has declined dramatically," he said. "This is a critically important development." While noting "with satisfaction and hope for the future" that the violence had dropped overall in the past month, he warned that "a disturbing level" still persists.

Palestinian militants continued to fire mortars and rockets against Israeli settlements and targets inside Israel, while Israel continued to carry out illegal extrajudicial killings, demolish houses and construct the "barrier" in the West Bank with "worrisome consequences" for the population there.

As well as the smooth Palestinian transition Mr Prendergast cited as the other "catalyst" Israeli Prime Minister Ariel Sharon's plan to withdraw from the Gaza Strip, noting that this "can represent a step forward - with highly symbolic, precedent-setting significance - on the road towards ending the occupation that began in 1967 and towards achieving lasting peace in the Middle East.

He said the UN, together with its diplomatic quartet partners in the roadmap peace plan - the European Union (EU), Russia and the United States - stood ready to maintain the momentum.

"We believe now is the time to engage actively, help the process along and determine how best the international community can contribute to the revival of a sustainable peace process between Israelis and Palestinians," he added.

Prendergast noted that President Assad had reiterated a willingness to resume negotiations with Israel. "We believe that the outstretched Syrian hand should be grasped," he said.