By Fredrik Dahl
VIENNA (Reuters) - They may be joining forces in a new Middle East conflict, but Arab nations are defying the United States at a major meeting of the U.N. nuclear watchdog by trying to crank up pressure on Israel over its assumed atomic arsenal.
Western diplomats say a vote on an Arab initiative to single out Israel for criticism at the Sept. 22-26 annual conference of the 162-nation International Atomic Energy Agency (IAEA) could be close, a year after it went down to defeat.
An Arab resolution on what it calls Israeli Nuclear Capabilities - opposed by Washington and European states - would be non-binding even if it were to be approved in a vote expected later this week.
However, intense lobbying by both sides underlines its symbolic geo-strategic significance and deep divisions on the issue of nuclear weapons in the Middle East, where some Arab countries joined the United States this week in air strikes on radical Islamist insurgents.[ID:nL6N0RP4D2]
Israel is believed to possess the Middle East's only nuclear arsenal, drawing frequent condemnation by Arab countries and Iran as an alleged threat to regional peace and security.
The Jewish state is the only Middle Eastern country outside the nuclear Non-Proliferation Treaty (NPT).
A draft text circulated at the IAEA meeting by 18 Arab states expressed "concern about the Israeli nuclear capabilities and calls upon Israel to accede to the NPT and place all its nuclear facilities under comprehensive IAEA safeguards."
U.S. and Israeli officials see Iran's nuclear activity as the main proliferation threat in the Middle East. They have warned that the Arab resolution, if adopted, could set back wider efforts to ban weapons of mass destruction in the region.
Israel has never confirmed or denied having nuclear weapons under a policy of ambiguity aimed at deterring longtime Arab and Islamic adversaries. It says it would only join the NPT after a broader Middle East peace settlement.
The head of the Israeli delegation, Atomic Energy Commission head Shaul Chorev, criticized what he called a "continuous anti-Israel campaign waged" by Arab members of the IAEA.
"Arab insistence on 'Israeli Nuclear Capabilities' negates dialogue, trust and confidence," he told delegates this week.
Last year, Arab states submitted a resolution on Israel to the gathering in Vienna for the first time since 2010 to signal their frustration at the lack of movement in efforts to ban nuclear bombs and other weapons of mass destruction in the Middle East. But it was rejected by an eight-vote margin.
Western diplomats say the Gaza war between Israel and Islamist Hamas militants in the enclave that ended last month may, however, influence the voting of some wavering countries, although there is no direct link between the two issues. But one envoy said he still expected the resolution to be defeated.
Gaza medical officials say 2,100 Palestinians, most of them civilians, were killed in the 50-day conflict; 67 Israeli soldiers and six civilians were also killed. Israeli shelling destroyed wide areas of the small, densely populated enclave.
Iran, an NPT signatory unlike Israel, denies accusations that it has been working to develop an atomic bomb capability. It is now negotiating with six world powers, including the United States, to end the dispute over its nuclear program.
(Editing by Mark Heinrich)