Iran delivered a letter to world powers today but gave no concrete reply to a demand to freeze its nuclear activity, a defiant step that the United States has warned could lead to more sanctions.
Iran handed the letter to European Union foreign policy chief Javier Solana in response to an offer in June by major powers to refrain from moving to impose more UN penalties if Iran froze expansion of its nuclear work.
Extracts of the one-page letter showed Iran gave no firm reply to the offer but instead promised to give a "clear response" at an unspecified date.
"Iran is ready to provide a 'clear response' to your proposal at the earliest possibility, while simultaneously expecting to receive your 'clear response' to our questions and ambiguities as well," according to an extract of the letter. "Such mutual clarification can pave the way for a speedy and transparent negotiating process with bright prospect."
The major powers say they fear Tehran wants to build an atomic bomb. But Iran, the world's fourth-largest oil producer, insists it is only seeking to master nuclear technology to generate electricity.
Mr Solana's office confirmed he received the letter but declined to provide any details.
US State Department spokesman Gonzalo Gallegos reiterated that Iran faced more sanctions if it did not give a positive response. Mr Gallegos said the United States would join a conference call with other senior officials from China, Russia, France, Germany and Britain tomorrow when the major powers would decide how to proceed.
Tehran has repeatedly refused to halt its atomic work, prompting the UN Security Council to impose three rounds of penalties on Iran since 2006. The United States also maintains its own sanctions against Iran.
"If we don't receive a clear message from them, we will have no choice but to pursue additional measures," Mr Gallegos said.
Diplomats cautioned it would be difficult to get through a fourth round of Security Council sanctions against Iran because of reluctance from Russia and China, as well as Germany.
One Western official who had seen the letter said it added "absolutely nothing" and that no concrete proposals were made by Tehran to resolve the impasse. The official said the letter also failed to provide any real response to the offer made by world powers of trade, financial and diplomatic incentives in exchange for a freeze of its uranium enrichment activities.
An Iranian official also said the letter did not address the demands by world powers. "The letter handed over is not an answer to the offered package. The letter does not mention the freeze-for-freeze issue," the Iranian official said.
The freeze proposal was seen as a stepping stone to full negotiations. But the Iranian official said the idea was also not raised in telephone talks yesterday between Mr Solana and Iran's chief nuclear negotiator, Saeed Jalili.
"During the call, Jalili expressed his readiness to start formal talks," the official said, adding he expected further contact between the two sides in the next few days.
The six powers have said formal talks on the incentives can start only once Iran suspends uranium enrichment, the part of the program that most worries the West because it has military and civilian uses.
In another development, a UN. nuclear watchdog official will go to Iran on Thursday. The International Atomic Energy Agency declined to specify the purpose of the visit by Olli Heinonen, its deputy director overseeing inspections of Iran's nuclear program.