"We are... encouraging all board members to make firm statements to call on Iran" to negotiate on the six-nation proposal, according to a document outlining the U.S. position.

Last week, European Union foreign policy chief Javier Solana presented a package of incentives, agreed by five UN Security Council permanent members -- Britain, China, France, Russia and the United States -- and Germany, in exchange for Iran's suspension of uranium enrichment.

The U.S. document said the five permanent Security Council members and Germany "have agreed to pursue measures, including at the UN Security Council, (to) pressure the Iranian regime to change course" in the event that Tehran declines the offer.

The full suspension of enrichment-related and reprocessing activities was "essential if Iran is to succeed in building international confidence." the document said.

Another document, issued by Britain, France and Germany, also warned that "the Security Council will have no choice but to increase the pressure on Iran" if Tehran remained defiant.

"The most important step for building international confidence will be for Iran to refrain from all enrichment-related and reprocessing activities until international confidence is restored," it said.

Iran said on Monday ahead of the International Atomic Energy Agency (IAEA) meeting that it would not compromise on its right to enrich uranium.

"Iran's view on the nuclear fuel cycle has been announced... we have obtained this technology, it is our obvious right and we do not negotiate over our obvious nuclear rights," Iranian government spokesman Gholamhossein Elham said in Tehran.

Iran's envoy to the IAEA, Ali Asghar Soltanieh, had earlier urged the body to avoid "politically motivated statements that could spoil the environment" for a diplomatic solution.

During the week-long meeting, the UN nuclear watchdog is to debate Iran but pass no resolutions in an attempt to avoid any diplomatic upset while Iran is considering the proposal to resolve the nuclear dispute, diplomats said.