Iran increased its own pressure against referral, threatening to restart uranium enrichment - a possible pathway to nuclear arms, diplomats accredited to the agency said.
They said Iran also warned it could block access for IAEA inspectors it had previously agreed to under a document that Iran has not yet ratified.
The diplomats - who sought anonymity because their information was confidential - said on Friday that both threats were contained in unsigned letters and shown by a member of the Iranian delegation to the IAEA head, Mohamed Elbaradei.
If signed and submitted, the letters become part of the official record.
The EU motion - a draft resolution to the IAEA's board of governors - calls on the 35-nation board to consider reporting Iran to the council.
The motion mentions non-compliance with provisions of the Nuclear Non-Proliferation Treaty (NPT) and suspicions that Iran's nuclear activities could threaten international peace and security, according to a draft copy obtained by the Associated Press.
Russia and China would use their
veto powers to avoid sanctions
A Bush administration official, speaking on condition of anonymity because negotiations were in progress at the time, said the United States was willing to accept the motion as an interim measure.
Any resolution still must be accepted by the board before it has validity.
The board agreed to reconvene on Saturday and the Europeans, backed by the Americans and their allies, were expected to call then for approval by consensus or - if that proved impossible - for a vote.
The board normally makes decisions by consensus, but the divisive nature of the draft was expected to result in a vote, which the Europeans were expected to win against Iran's allies at the IAEA.
The Security Council could impose sanctions if it determines that Iran violated the Nuclear Non-Proliferation Treaty (NPT), but veto-carrying council members Russia and China - which oppose even referral to the council - were certain to vote against such action.
To date, the draft made no mention of sanctions.
Still, it was unequivocal in saying that - unless Iran ends uranium conversion and clears up questions remaining about its past nuclear activities - the grounds exist for Security Council referral.
A nation's failure to comply with the NPT is automatic grounds for a report to the Security Council under IAEA statutes, and the draft said "Iran's many failures and breaches of its obligations ... constitute non-compliance".
Additionally, Iran's spotty record on cooperating with an IAEA probe since that began in 2002 has resulted in an "absence of confidence that Iran's nuclear programme is exclusively for peaceful purposes," the document said.
That finding puts Iran "within the competence of the Security Council, as the organ bearing the main responsibility for the maintenance of international peace and security," the text said.
EU draft demands
The draft did not specify a time frame for referral, but outlined what Iran must do to avoid being brought before the Security Council, including:
"...access to individuals, documentation relating to (nuclear) procurement, dual use equipment, certain military owned workshops and research and development locations"
- Giving IAEA experts "access to individuals, documentation relating to (nuclear) procurement, dual use equipment, certain military owned workshops and research and development locations";
- A return to "full and sustained suspension of all enrichment-related activity ... and reprocessing activity";
- Allusions to the resumption by Iran last month of uranium conversion;
- A precursor of enrichment, which can result in either nuclear fuel or the fissile core of warheads;
- Iran's ratification of the additional agreement with the IAEA giving its inspectors the right to look more closely at Iran's nuclear activities.
From the tone of the draft submitted, it appeared the European Union decided to go with a harsher text, even at the risk of alienating Russia.
The Europeans for years avoided US demands for support in its push to haul Iran before the Security Council.
They reluctantly swung behind Washington last month, after Tehran effectively walked away from talks with Britain, France and Germany meant to reduce suspicions about its nuclear aims and began uranium conversion.