The International Atomic Energy Agency's (IAEA) 35-nation board of governors separately approved a deal allowing for more intrusive inspections of Iranian nuclear sites and said it was now ready to be signed by Tehran.
The IAEA meeting was adjourned until Wednesday after the United States and Europe's big three -- Britain, France and Germany -- failed in two days of intense, closed-door negotiations to agree on a resolution in response to the watchdog's report detailing almost two decades of hidden Iranian nuclear activities.
Addressing the board, US Ambassador to the IAEA Ken Brill said Iran could not be seen as "a state that tried in good faith to meet its obligations" under international nuclear non-proliferation agreements, according to a copy of his speech given to reporters.
"Iran's breaches of its obligations have been brazen and systematic and far from merely 'technical' ones," Brill said.
The United States wants Iran to be declared in "non-compliance" with the nuclear Non-Proliferation Treaty (NPT), a move that could see the issue put before the UN Security Council, which could slap sanctions on Iran.
But many countries, led by Britain, France and Germany, think that taking the issue to the Security Council could cause a backlash, prompting Tehran to cut off cooperation with the IAEA.
The IAEA board is considering a report from its chairman Mohamed ElBaradei that outlines 18 years of hidden suspect nuclear activities by Iran, including making small amounts of plutonium and enriched uranium.
Brill said the report "makes unequivocally clear that Iran chose, as a matter of government policy sustained for well over a decade, to violate its safeguards obligations in full knowledge that its actions and omissions were violations."
ElBaradei said the IAEA has no "evidence," however, that Iran is developing nuclear weapons, with investigations continuing.
But Brill said there clearly was evidence but no "proof" and that ElBaradei's comment had been misinterpreted.
Iran has cooperated fully with the IAEA since October 21, when it struck a deal with Britain, France and Germany to agree to wider, snap inspections and suspend the enrichment or uranium, in return for promises that the IAEA would not bring it before the Security Council, diplomats said.
After the the IAEA board approved the additional protocol that allows for snap inspections, agency spokeswoman Melissa Fleming said it was now "ready to be signed".
But Iran refused to set a date for signing the text on the new inspections regime until its sees what sort of a resolution the board is to pass on its non-proliferation violations.
Iran's ambassador to the IAEA Ali Akbar Salehi told reporters the protocol and the resolution were a "package" together.
In Tehran, Iranian Foreign Minister Kamal Kharazi said that if EU countries fail to prevent Iran from being declared in non-compliance, Tehran will abandon commitments made to the IAEA.
The United States, however, "is looking for some pretty strong language and is willing to compromise only to a point," a Western diplomat said.
"If we're not going to have an extremely strong resolution, why have a resolution at all," he said.
A key sticking point in the so-called Euro 3's draft resolution is its saying that if Iran continues to cooperate, the issue of its compliance should stay with the IAEA.
The text says that should ElBaradei "report that there have been further significant failures, the board of governors would meet immediately and decide upon measures to be taken," according to a copy shown to reporters.
A diplomat said this formulation, however, was not enough since the term "significant failures" was vague.
"A failure is a failure," the diplomat said, stressing that the resolution should also unambiguously say when the matter would go to the Security Council.