The UN's nuclear watchdog was due to vote today on an EU resolution requiring Iran to be reported to the Security Council over what the West fears is a covert atomic weapons programme.
Despite Iranian threats to begin enriching uranium if the resolution that could eventually lead to sanctions against the Islamic country is passed, the EU's top powers and Washington were confident it would be approved.
The meeting has widened the split between rich Western nations and poorer developing nations led by Russia, China, India and South Africa, which disagree with Washington and Europe on how to deal with Iran.
And diplomats said there was a possibility that Russia, China and other non-aligned members of the International Atomic Energy Agency's (IAEA) 35-nation board might not show. The meeting needs two-thirds of the members present for a quorum.
But most said the simple majority needed for approval should be reached.
"We have a majority of votes, but no consensus. We tried to win over Russia, but did not succeed," an EU diplomat said. "Most likely they will vote against it."
Iran denies seeking atomic bombs and says its nuclear programme is only for generating electricity. However, it concealed its atomic fuel programme from the IAEA for 18 years.
Russia, which is building a $1 billion nuclear reactor at Bushehr in Iran and has much to gain from Iran's plans to develop atomic energy, is a fierce opponent of referring Iran's programme to the Security Council.
China, which needs Iran's vast energy resources for its own booming economy, also opposes the Western drive against Iran.
Both countries fear a UN referral will cause the standoff over Iran's programme to escalate into an international crisis.