The United States in turn has accused Iran of trying to bully the board of the International Atomic Energy Agency (IAEA), meeting in Vienna, and said such tactics increased suspicions that Tehran was secretly making weapons.
"The basic message that Iran is sending is that they have something to hide and they're going to use any means they have, including intimidation, to keep things from coming to light," said Kenneth Brill, US ambassador to the UN in Vienna, on Wednesday.
"People who are trying to produce electricity for light bulbs don't engage in this kind of behaviour," he said.
Earlier on Wednesday, in his toughest warning to the IAEA yet, Iranian President Muhammad Khatami described as "very bad" a resolution drafted by Britain, Germany and France that "deplores" Iran's inadequate cooperation with the agency.
"If this resolution passes, Iran will have no moral commitment to suspend uranium enrichment," he told reporters.
"We have no intention of using nuclear technology for military use," he said. "We will continue our cooperation with the agency in the framework of the law and our rights."
In Vienna, several diplomats said Europe's big three states were holding backroom meetings with board members to prepare a third draft of the resolution that could be debated on Thursday and would be acceptable to the entire board - and the Iranians.
"If this resolution passes, Iran will have no moral commitment to suspend uranium enrichment"
Hossein Mousavian, secretary of the foreign policy committee of Iran's Supreme National Security Council told reporters what the main sticking point was. Iran wants a paragraph deleted that urges Iran to "reconsider" plans to operate a uranium conversion plant and begin construction of a heavy-water research reactor.
Iran says the resolution under discussion in Vienna has blown technical shortcomings out of proportion and is driven by an anti-Iranian political agenda in the US.
"The IAEA resolution is very bad ... (it) violates our country's rights," Khatami said. "Iran's nuclear row is political, and there is a political will behind it to stop us accessing peaceful nuclear technology," he said.
Iran, which denies seeking weapons, says it wants to produce low-grade enriched uranium as fuel for nuclear power reactors. But Washington and many European states fear it could use the technology to make highly-enriched, bomb-grade uranium.