Iran may withdraw a counter-offer it made to the International Atomic Energy Agency in response to proposals from the major powers for the supply of nuclear fuel, its IAEA envoy warned on Thursday.

"Iran's proposal for a simultaneous exchange on Iranian soil of our low enriched uranium for fuel enriched to 20 percent is still on the table but it will not stay there forever," Ali Asghar Soltanieh said, quoted by Mehr news agency.

His words echoed similar warnings of a time-limit from the major powers.

"Any development which might disturb the climate of cooperation" would prompt Iran to withdraw the offer, he added, alluding to the threat of new sanctions being levelled by Western governments with Russian support.

Last October, the IAEA drew up a plan for Iran to ship out most of its stockpiles of low enriched uranium in return for the supply by France and Russia of uranium enriched to the 20 percent level required for a Tehran medical research reactor.

Iran baulked at the stipulation that it ship out the uranium before receiving any fuel and last month started enriching uranium to 20 percent itself.

The move, launched before the IAEA could install monitoring equipment, angered the European Union and the United States which on Wednesday began intense lobbying for tough new UN sanctions.

For Western governments worried that Tehran might otherwise covertly enrich some of the stocks to weapons grade, the requirement to ship out most of Iran's stockpiles before receiving any fuel is the main element of the IAEA plan.

US Secretary of State Hillary Clinton said on Wednesday it was vital that a fourth round of UN sanctions be enforced to apply pressure on Iran to accept the IAEA plan.

"Only after we pass sanctions in the Security Council will Iran negotiate in good faith," she said.

But veto-wielding UN Security Council member China has been holding out, insisting the diplomatic path should be pursued, and Clinton acknowledged this week that it might take months before a new round of sanctions is agreed.

Brazil, a current member of the Security Council but without veto power, too has thrown its weight against sanctions.

Before a meeting in Brasilia with Clinton on Wednesday, President Luiz Inacio Lula da Silva warned the international community not to "push Iran into a corner."

"Peace in the world does not mean isolating someone," said Lula, whose country has its own nuclear energy programme.

Iran strongly denies Western suggestions that its nuclear programme is cover for a drive to build an atomic bomb.

earlier related report
Brazil, US clash over how to deal with Iran
Brasilia (AFP) March 3, 2010 - Brazil and the US clashed Wednesday over how to rein in Tehran's suspect nuclear ambitions as Brazilian President Luiz Inacio Lula da Silva warned the world not to "push Iran into a corner."

In talks with US Secretary of State Hillary Clinton, Lula and his Foreign Minister Celso Amorim backed continued international negotiations to ensure Iran does not enrich uranium to the point it can build a nuclear bomb.

Lula set a tough tone for his and Amorim's talks with Clinton when he said it is "not prudent to push Iran into a corner. It is prudent to make it so that Iran continues to negotiate."

In a combative press conference with Amorim, a stern-faced Clinton retorted that the US-led drive to impose a fourth set of UN sanctions on the Islamic Republic was the only way to bring it back to the negotiating table.

"Only after we pass sanctions in the Security Council will Iran negotiate in good faith," Clinton said in a foreign ministry briefing room where she was continually pressed by local journalists on Washington's hard stand.

Clinton echoed Amorim when she said both shared the goal of preventing Iran from becoming a nuclear weapons country, but said the two differed in how to attain it.

"Once the international community speaks in unison around a resolution, then the Iranians will come and begin to negotiate," she said, raising her voice.

"So we want to get to the negotiation. We just think the best path is through the United Nations Security Council."

She also appeared to suggest Brazil and other countries were falling for what the US consider is Iranian antics.

"We see an Iran that runs to Brazil, an Iran that runs to Turkey, and an Iran that runs to China telling different things to different people to avoid sanctions," she said.

Brazil is a current voting member on the 15-strong UN Security Council, though it is not one of the five permanent veto-wielding members, which are Britain, China, France, Russia and the United States.

But China appears to stand alone among the permanent members in resisting sanctions, with Russia appearing to move toward them.

When asked why Brazil was going against the growing consensus, Amorim responded sharply, "It's not a matter of Brazil refusing to join a nuclear consensus."

Rather, he said it was a question of determining whether coercive measures like sanctions would work.

"Our view is that sanctions, in general, are counterproductive," he said, adding that Brazil believed diplomacy was "worth the effort."

"The director of the International Atomic Energy Agency will come to Brazil and I am going to suggest to him that he convene a meeting with the Iranian negotiators, perhaps with the presence of some new interlocutor," he said.

"Once the international community expresses itself, sends a clear message, by means of a UN resolution, the Iranians will negotiate. And that is why the best path is through the UN Security Council," he said.

A top State Department official quoted a senior Brazilian official whom he would not name as saying Brazil's position was "not etched in stone" but would probably change only after China drops its opposition.

Speaking on the plane from Brasilia to Sao Paulo, the official told reporters on the condition of anonymity that he also doubted Brazil would change its position before Lula visits Iran on May 15.

Clinton's visit to Brazil was preceded Friday by William Burns, the US undersecretary of state for political affairs, who leads US consultations on Iran among the permanent five members of the UN Security Council plus Germany.

The so-called P5-plus-1 group has for years spearheaded efforts to halt Iran's nuclear program, which the west fears masks a drive for a nuclear weapon but which Iran says is for peaceful nuclear energy.

A senior European diplomat in Washington told reporters last week that China might abstain in a UN sanctions vote, along with Brazil, Turkey and Lebanon.

Brasilia was Clinton's fourth stop on a six-nation Latin America tour, following visits to Chile, Argentina and Uruguay.

Clinton and Amorim signed agreements to curb global warming, increase opportunities for women and promote economic development in both Latin America and Africa, US officials said.

The secretary arrived later at Sao Paulo's Zumbi dos Palmares University, the country's only Afro-Brazilian university, for a town-hall style meeting with students that will be broadcast on Brazilian television.