The aim of its announcements on Wednesday was to show that international sanctions are failing to stop it making progress in nuclear know-how despite trade embargoes and to strengthen its hand in any renewed negotiations with six world powers.
"The fourth generation of domestically made centrifuges have a higher speed and production capacity ... It will be unveiled on Wednesday," state television said, without giving a source.
It was the latest display of Iran thumbing its nose at a series of U.N. resolutions demanding that it suspend uranium enrichment and open up to U.N. nuclear inspectors.
Last year, Iran installed two newer models for large scale testing at a research site near the central town of Natanz. But it remains unclear whether Tehran, subject to increasingly strict trade sanctions, has the means and components to make the more sophisticated machines in industrial quantity.
If Iran eventually succeeded in introducing modern centrifuges for production, it could significantly shorten the time needed to stockpile enriched uranium, which can generate electricity or, if refined much more, nuclear explosions.
Tehran has worked for several years to perfect faster, more reliable centrifuge machines than the 1970s-vintage P-1 model it now uses to refine uranium.
Western analysts were skeptical of the proclaimed advances.
"We have seen this before. We have seen these announcements and these grand unveilings and it turns out that there was less there than meets the eye. I suspect this is the same case," said Shannon Kile at the Stockholm International Peace Research Institute (SIPRI).
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