The US has dismissed the nuclear achievements demonstrated by Iran as something not terribly new and impressive.
Washington expected to learn more from the International Atomic Energy Agency (IAEA) inspectors currently on the ground in Iran about what the country demonstrated on Wednesday, Xinhua quoted US State Department spokeswoman Victoria Nuland as saying.Iran's move laid bare the pressure of its international and diplomatic isolation, as the "unprecedented" sanctions are still growing, she said.
"Well, I can't speculate any further as to Iran's motives behind its various actions. But our view on this is it's not terribly new, and it's not terribly impressive," she said, adding "This strikes us as calibrated mostly for a domestic audience."
At a ceremony held in Tehran, Iranian President Mahmoud Ahmadinejad unveiled nuclear fuel rods, new generation of centrifuges and a number of radioactive medicines for the treatment of cancer.
He also fed a homemade fuel rod made out of 20% enriched uranium into the core of the Tehran Research Reactor.
Nuland also confirmed that EU foreign policy chief Catherine Ashton had got a response from Saeed Jalili, Iran's chief nuclear negotiator, to the letter she sent in October last year, a move the West had been demanding as a precondition for the resumption of talks with Iran over its controversial nuclear programme.
"Our interest is in Iran abiding by its international obligations, renouncing its interest in nuclear weapons and returning to the international community," White House spokesman Jay Carney said.
"And that path remains open to Iran as long as it is interested in talks that they would approach in a constructive manner," he told reporters aboard Air Force One en route to Wisconsin state.
The West suspects that Iran is developing nuclear bombs under the cover of its nuclear programme. But the Islamic republic insists the programme is only for power generation and medical purpose.
EU gets letter from Iran for N-talks
In another development the European Union (EU) has received a letter from Iran asking it to restart the nuclear talks.
"We received the letter today and we're studying it, we're consulting with our E3+3 partners," Xinhua quoted Maja Kocijancic, spokeswoman of EU foreign policy chief Catherine Ashton as saying.
The EU last month decided to impose additional sanctions on Iran, focusing on its central bank and oil exports.
Up to now, some 400 Iranian assets in the continent have been frozen and 113 people subjected to visa ban and asset freeze.
The European Union is an economic and political confederation of 27 member states which are located primarily in Europe.
The E3+3 countries include Britain, US, France, Germany, China and Russia.