VIENNA (Reuters) - Iran has started using extra machines installed this year to enrich nuclear material to higher levels more efficiently, in violation of United Nations sanctions, the U.N. nuclear agency said on Monday.
The International Atomic Energy Agency (IAEA) said Iran was using a second set, or "cascade", of centrifuge machines at its Natanz pilot plant to enrich uranium to 20 percent purity, a process that has heightened Western concerns that it is trying to develop nuclear weapons.
Iran has been producing low-enriched uranium (LEU) for some time and said in February it had started enriching uranium to the 20 percent level to make fuel for a medical research reactor. It says its work is for peaceful purposes only.
"The IAEA can confirm that on 17 July, when agency inspectors were at (the pilot plant), Iran was feeding nuclear material to the two interconnected 164 machine centrifuge cascades," spokeswoman Gill Tudor said, confirming a report last week by the Washington-based think tank the Institute for Science and International Security.
She added this was "contrary to U.N. Security Council resolutions affirming that Iran should suspend all enrichment related activities".
Using two cascades allows leftover LEU to be re-fed into the machines, obtaining its full potential and making the work more efficient. Under the current setup, the output and enrichment level stay the same and the work is monitored by the IAEA.
However, the West fears Iran aims to stockpile material to enrich later to 90 percent purity, the level needed for a nuclear weapon, because it lacks the capability to produce the fuel plates needed for the medical reactor.
Analysts say now that Iran has reached the 20 percent mark, it could advance to weapons-grade level in months since low-level enrichment is the most time-consuming and technically difficult stage of the process.
Tehran has said it was forced to enrich uranium to 20 percent purity after the breakdown of a deal with Western powers and the IAEA, under which it would have sent 1,200 kg of LEU abroad in return for fuel rods for its medical reactor.
It tried to resurrect the swap in a deal with Turkey and Brazil but this was not enough to prevent the U.N. Security Council from imposing a fourth round of sanctions in June.
Iran said on Monday that its first atomic power station would come on stream by September after years of delays.
"Right now the equipment of the Bushehr power plant is being inspected and I am announcing decisively that it will become operational by September," Iran's Atomic Energy Organisation head, Ali Akbar Salehi, said according to state TV's website.
Russia agreed to build the 1,000-megawatt reactor 15 years ago but delays have plagued the $1 billion project and diplomats say Moscow has used it as a lever in relations with Tehran.
Salehi said he expected talks with the so-called Vienna group -- France, Russia the United States and the IAEA -- to restart in the next two or three weeks on the fuel swap plan.
Western officials have raised doubts about the potential for fresh talks now that Iran has started 20 percent enrichment and its LEU stockpile has continued to grow.
(Additional reporting by Robin Pomeroy in Tehran; editing by Andrew Dobbie)
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