To get broader approval this year, Egypt, which sponsored the session, deleted clauses urging all Middle East nations not to make or test nuclear arms or let them be deployed on their soil, and big nuclear arms powers not to foil such steps.
But efforts to achieve consensus collapsed after competing Israeli and Arab additions, which included urging all regional states to comply with obligations to the NPT, and all nations to accede to the global treaty.
Called the "Application of IAEA safeguards in the Middle East", the resolution also underlined the importance of a peace process between Israel and Arabs in establishing a nuclear weapons-free zone in the region.
But almost all Arab League states walked out of the Vienna assembly hall before the vote over Israeli-sponsored amendments were pushed through by Western states.
"How could we approve a call on us all to obey our international obligations when Israel itself refuses to adhere to any non-proliferation standards. This undermines the IAEA's credibility," one Arab diplomat said.
A senior Western diplomat said: "The call for compliance with obligations was a change from versions of this resolution in previous years in that it is a clear signal to Iran and Syria."
Iran and Syria, both NPT members, are under IAEA investigation over suspicions of covert intentions to make atomic bombs. They deny the allegations.
One European diplomat said: "It has been a circus, the worst conference in the history of the IAEA. I've never seen such animosity.
"But it reflects the unilateral character of the age we are living in, plus the lack of a true peace process."
Those who approved the resolution included te majority of Western states, a handful of Asian, Latin American and African countries, plus Iran and Egypt.
Those who Abstained included Israel, the US, and Syria.
Israel is widely assumed to have the Middle East's only nuclear arsenal, though it has never confirmed or denied it.
Israel says that while a nuclear-free Middle East is a commendable idea, it is not feasible as long as some Arab neighbours continue not to recognise the Jewish state.
Arab diplomats point to a chronic imbalance of power in the Middle East caused by unchecked Israeli power and say it breeds instability and spurs others to seek mass-destruction weaponry.
A second resolution presented later in the day, which would have branded "Israel's nuclear capabilities" a threat, was kept from a floor vote by a Western-backed "no-action" motion carried by a 46-43 margin.
The same measure at last year's assembly was hastily shelved by Arab diplomats in the face of a similar blocking manoeuvre.