VIENNA: Syria accused Israel of posing a "grave and serious threat" through its undeclared atomic arsenal Monday, at a session between the Jewish state and its Arab neighbors meant to narrow differences on creating a Mideast nuclear weapon-free zone, officials said.

Aside from Iran, which is boycotting the meeting, Syria is Israel's bitterest Mideast rival, and Syrian delegate Bassam al-Sabbagh voiced rhetoric similar to standard Arab criticism of Israel. But officials reporting on the closed meeting said that except for Syria and Lebanon, its lockstep ally, other Arab nations speaking at the meeting were lower-key than usual in chastising the Jewish state for refusing to open its nuclear program to U.N. perusal.

Israel did not speak at the morning session. But one of the officials - who asked for anonymity to report on the International Atomic Energy Agency meeting - said the atmosphere was "much less confrontational, much less hostile" than at other IAEA gatherings focused on the Middle East, which traditionally see Muslim nations speaking with one strongly critical voice about Israel's nuclear capabilities.

Wide chasms separate the two sides. Israel says peace must be established in the Mideast before talks on a nuclear weapons-free zone can be concretely discussed. The Arabs say the two topics are independent.

In toning down their comments, most Mideast participants at the 97-nation meeting appeared to be heeding an appeal by IAEA chief Yukiya Amano. In opening remarks made available to reporters, Amano urged Mideast nations to focus on "fresh thinking," adding he hoped they would be able to move "beyond simply restating long-established positions."

Officials and participants warned against high expectations at the gathering, which is hearing presentations on already established nuclear-free zones elsewhere as a way of stimulating discussion on the Middle East and is not meant to reach any decisions.

A decision last year by the 189 members of the Nuclear Nonproliferation treaty to convene a U.N.-sponsored conference on establishing a Middle East nuclear-free zone in 2012 was an incentive for most of the region's Muslim nations to meet this year with Israel for the exploratory Vienna talks.

Arab countries and Iran are aware of the potential of using the 2012 U.N. conference as a platform to pressure Israel to fulfill their long-standing demands: joining the Nonproliferation Treaty, acknowledging that it has nuclear weapons and allowing IAEA inspectors to probe their atomic activities.

Israel is unlikely to do any of that. It remains unclear whether it will even attend the 2012 talks and is at the Vienna meeting only under the stipulation that it remain a nonbinding give-and-take on the issue of nuclear free zones in general.

The official said that early discussions Monday touched on a main point of division between Israel and the Arabs - whether the Jewish state needs to join the treaty as a prerequisite to creation of such a zone.

He said that presenters for Argentina and South Africa, talking about their own regional zones, suggested that based on the experience of their own regions treaty membership was not needed to begin talks.

Israel is commonly considered to be the only Middle East nation with atomic weapons - and its secretive nuclear program has long been a heated subject with Arab neighbors.

The Arabs have urged Israel to open up to international inspection. Israel in turn says that Iran is the greatest threat to the region through its refusal to heed U.N. Security Council resolutions demanding it stop activities that could be used to make nuclear weapons and suspected research and development of such capabilities. Tehran denies any interest in such arms.