The UN's nuclear watchdog said today Iran had failed to meet a February 21st deadline to suspend uranium enrichment.
The International Atomic Energy Agency said in a report Iran had installed two cascades, or networks, of 164 centrifuges in its underground Natanz enrichment plant with another two cascades close to completion.
Iranian protesters hold a picture of Iran's Supreme Leader Ayatollah Ali Khamenei and a placard reading
This represented efforts to expand research-level enrichment of nuclear fuel into "industrial scale" production.
It said Iranian workers lowered into the plant an 8.7-tonne container of uranium hexafluoride gas to prepare to start feeding centrifuges, which can enrich the material into fuel for power plants or, if refined to high levels, for bombs.
Iran's defiance of a 60-day deadline set by the UN Security Council when it banned nuclear technology transfers to Iran on December 23rd will expose Iran to wider sanctions over its atomic energy programme, which the West fears is a front for assembling atom bombs.
Tehran says it is seeking nuclear-generated electricity. "Iran has not suspended its enrichment-related activities," said the confidential IAEA report.
The report said Iran had said it intended to have 3,000 centrifuges, divided into 18 cascades, installed and brought "gradually into operation" by May this year.
The 3,000 centrifuge machines will lay the basis for "industrial-scale" fuel production involving some 54,000.