A day after claiming it had begun producing nuclear fuel on an industrial scale, Iran has announced even more ambitious plans, including tens of thousands of new centrifuges.
The claims have been met with scepticism by the international community which sees them as a provocation to their demands for Iran to halt uranium enrichment.
The West fears Tehran is trying to produce an atomic bomb, which Iran denies.
Russia has said it will wait and see what UN inspectors have to say before forging an opinion.
Two inspectors from the United Nations nuclear watchdog the IAEA have arrrived in Iran to inspect the Natanz uranium enrichment plant where Iran claims the atomic work is underway.
There has been no confirmation so far that enrichment has started. Iran insists the purpose of its nuclear programme is peaceful.