Iran asserted on Sunday that it has already acquired the sensitive technology to produce its own nuclear fuel and said it would be "irrational" to agree to surrender such a capability in exchange for supplies from overseas.
"One should not put one's fate in the hands of others. It would irrational," said foreign ministry spokesman Hamid Reza Asefi.
"We have the technology and there is no need for us to beg from others. This suggestion is good for countries that do not have this technology, but we do not need their generosity and help," he added.
Asefi was reacting to US Democratic presidential candidate John Kerry, who has suggested providing Iran with nuclear fuel to generate electricity if the country agreed to give up its controversial work on the nuclear fuel cycle.
In a debate with US President George W. Bush, Kerry said the United States should have joined a British-French-German initiative aimed at getting Iran to agree to stop work surrounding the enrichment of uranium.
Fuel cycle work for peaceful purposes is permitted under the nuclear Non-Proliferation Treaty (NPT), of which Iran is a signatory, but the process can also be used to produce the core of an atomic bomb.
But Asefi repeated the clerical regime's assertion that Iran needs to be self-sufficient when it comes to fuelling it atomic energy programme.
"What guarantees are there? Will they supply us one day, and then if they want to, stop supplying us another day?" he said.
Iran is under threat of being hauled before the UN Security Council amid widespread suspicions it is seeking the "option" to develop nuclear weapons. The country says it only wants to generate electricity.
In a resolution passed on September 18, the International Atomic Energy Agency (IAEA), which oversees the NPT, called on Iran to halt its uranium enrichment-related activities amid its ongoing investigations.
Iran suspended enrichment itself last year, but has continued to advance on other parts of the fuel cycle - including the conversion of yellowcake (uranium oxide) to produce the feed gas for centrifuges - and insists on its right to resume enrichment at any time.
Asefi repeated that "we have no taken a decision yet" on resuming enrichment, but cautioned the IAEA against putting too much pressure on Iran and provoking the country's powerful hard-liners.
Iran's parliament, controlled by conservatives, has begun putting together a bill forcing the reformist government to buck the IAEA demand and resume enrichment - a step certain to place Iran on a collision with the UN's nuclear watchdog.
"This bill is in its preliminary stages, and if the Majlis (parliament) approves it and the Guardians Council approves it and it becomes law, it is natural that the government is obliged to implement it," Asefi said.
He said the Europeans, who appear to be edging towards the tougher US stance, should "understand the internal circumstances" in Iran.