Iran's willingness to suspend nuclear enrichment is central to the major powers' proposed deal and Tehran would have to maintain that suspension throughout any negotiations, the US said today.
US State Department spokesman Sean McCormack refused to say if the deal includes a provision by which Iran might eventually be allowed to resume enrichment on its territory but said suspension is a "firm condition" of the major powers' offer to begin negotiations and "that condition would have to hold throughout any potential negotiations."
US President George W. Bush yesterday welcomed Tehran's response to proposals by six world powers to end a dispute over Iran's nuclear fuel enrichment as positive, but sounded a note of caution.
Tehran's chief negotiator said the proposals had positive points but contained ambiguities that must be removed.
"It sounds like a positive step to me," Mr Bush said. "So we'll see if the Iranians take our offer seriously. The choice is theirs to make," he told reporters in Laredo, Texas.
US President George W Bush
"I have said the United States will come and sit down at the table with them as long as they're willing to suspend their enrichment in a verifiable way."
The proposals include incentives and penalties aimed at persuading Iran to give up enriching uranium, which the West fears will be used to build atomic bombs, but Tehran insists is purely for civilian use.
European Union foreign policy chief Javier Solana presented Iran's chief negotiator Ali Larijani with the package, on behalf of the United States, Russia, China, Britain, France and Germany.
"The proposals had some positive steps in them and some ambiguities which should be removed," Mr Larijani said. "We hope, after we study the proposal in detail, we will have another round of talks and negotiations to achieve a balanced and logical conclusion."
Details of the proposals have not been made public, but German Foreign Minister Frank-Walter Steinmeier said he expected Iran to decide on the package by the end of June when foreign ministers from the Group of Eight industrialised nations are due to meet.
Washington, which broke ties with Tehran in 1980, wants a diplomatic solution and has offered to join direct talks with the Iranians but has refused to rule out military action.
Iranian officials said the incentives included access to aircraft parts needed to renovate its ageing civilian airline fleet and the chance to purchase US agricultural technology.
Diplomats have also suggested the package might include offers of nuclear reactor technology and security guarantees.
Western diplomats said the US was not expected to provide technology or equipment directly to Iran. Instead, Europeans and Russians would be the prime contractors.
An arms embargo against Iran was among the possible penalties, according to Washington diplomats.