Iran today announced an upgrade to its uranium enrichment machines, upping the ante even as UN experts were holding talks in Tehran on the Islamic republic's controversial nuclear drive.
The announcement comes despite a warning by Washington that an Iranian upgrade would violate UN resolutions and claims by Israeli Prime Minister Benjamin Netanyahu that Tehran is moving closer to making a nuclear bomb.
Atomic Energy Organization chief Fereydoon Abbasi Davani said new centrifuges with "a higher efficiency" were being installed at Iran's Natanz site, which uses the machines to enrich uranium gas by spinning it at supersonic speeds.
"The installation of new centrifuges at Natanz site started about a month ago... The process is ongoing," Abbasi Davani said in his announcement, which was reported by local media.
He did not reveal how many centrifuges were installed but said: "These centrifuges have a higher efficiency and are used specifically to enrich uranium to less than 5 percent, and not to 20 percent" - the purity regarded as being a short step from that which is required to make a nuclear bomb.
Iran had indicated to the UN nuclear watchdog its intention to install the new generation equipment, according to a document seen by AFP at the end of January.
The International Atomic Energy Agency document said that Iran informed it in a letter dated January 23 that "centrifuge machines type IR2m will be used in Unit A-22" at the Fuel Enrichment Plant at Natanz.
The IAEA replied in a letter dated January 29 asking for more information on the announcement.
Two days later White House spokesman Jay Carney warned that Iran's plans to install more modern equipment at Natanz was a "further escalation" in the showdown over its atomic programme.