Iran has announced it has developed faster centrifuges for uranium enrichment, signalling a determination to press on with its nuclear work despite possible new sanctions sought by Barack Obama, the US president.
In a ceremony marking Iran's National Day of Nuclear Technology on Friday, Mahmoud Ahmadinejad, the president, unveiled one of the new machines to a crowd of dignitaries, and praised scientists for making Iran a "nuclear country".
Ali Akbar Salehi, the head of Iran's Atomic Energy Organisation (AEOI), said: "The scientists of our country have been able to design a third generation of centrifuges, which successfully went through mechanical tests.
"These machines would have [isotope] separation capacity ... more than six times the earlier [first generation] ones, thus increasing output."
Iran's enrichment programme is of concern to the United States and its allies because it fears the technology could be used to produce material for an atomic weapon.
Salehi told Al Jazeera on Friday: "If we wanted nuclear weapons we would have said so. Our supreme leader, our leaders, our president have all indicated over and over again that we are not after nuclear bombs."
Bruno Pellaud, the former deputy director of the International Atomic Energy Agency (IAEA), told Al Jazeera that the so-called third generation centrifuge machines were a "major scientific achievement".
"But now the question is: Does it change the political outlook of the Iranian nuclear issue? Maybe not that much," he said.
"Iran already has enough centrifuges, thousands of them, with which they can achieve higher enrichment to go from the 20 per cent enrichment they have now to the 93 per cent" needed to produce nuclear weapons, Pellaud said.
Ahmadinejad said that 60,000 of the new generation centrifuges that were going to be installed at the Natanz enrichment plant were enough to fuel six nuclear power plants for a year.
The centrifuges Iran is using now are adapted from a 1970s design and have been prone to breakdowns.
Salehi said that the Iranian government had instructed the AEOI to look for locations where new enrichment facilities could be built, despite the looming threat of sanctions over increased production activities.
"We never welcome sanctions, nobody does. But the country has been accustomed to sanctions for the past 31 years. We have acheived great things under sanctions," he told Al Jazeera.
Western powers are seeking the support of Russia and China for a fourth round of UN sanctions against Tehran.
Obama, who hosts a nuclear security summit next week, wants them to back further measures to deter Iran from pursuing its nuclear programme.
"The history of the Iranian regime, like the North Korean regime is that you know, you apply international pressure on these countries, sometimes they choose to change behaviour, sometimes they don't," he told US ABC channel's "Good Morning America" earlier this week.
Obama signed a landmark disarmament treaty with Dmitry Medvedev, the Russian president, on Thursday limiting the number of each country's deployed nuclear warheads to 1,550.
"If America makes a crazy move, its interests will be endangered by Iran's allies around the globe"
The two men also pledged greater co-operation to persuade Iran to give up its uranium enrichment programme.
"If we are consistent and steady in applying international pressure ... over time, Iran, which is not a stupid regime, which is very attentive and watching what is happening in the international community, will start making a different set of cost-benefit analyses about whether or not pursuing nuclear weapons makes sense for them," Obama said.
Iran has shown few signs so far of bending to international calls for it to curb its nuclear programme.
An Iranian cleric on Friday said the Islamic Republic was counting on its "allies around the globe" to retaliate against any military strike by the US on its nuclear sites.
Ahmad Khatami, an Ahmadinejad loyalist, said the US would run into a quagmire if it attacked Iran - an option Obama has not ruled out to stop Iran from acquiring an atomic bomb.
"If America makes a crazy move, its interests will be endangered by Iran's allies around the globe," Khatami, a member of Iran's powerful Assembly of Experts, said.