Iran has launched a second batch of centrifuges at its pilot nuclear fuel plant despite possible UN Security Council sanctions, diplomats said.
Tehran fired up the new cascade of 164 interconnected centrifuges, which can enrich uranium for either power plant or nuclear bomb fuel, earlier this month to go with an initial network of 164, they said.
But Iran appeared to be only testing the second cascade, without feeding "UF6" uranium gas into it, as it has generally done with the first cascade, which first yielded a tiny amount of home-grown enriched uranium in April.
A senior diplomat familiar with UN nuclear inspections in Iran said Tehran remained a long way from "industrial scale" capacity that would signal its emergence as a nuclear power, as North Korea showed on Oct. 9 by detonating an atomic device.
"The second cascade was brought on line earlier this month but they appear to be just running it empty. That is, vacuum-testing to assess durability," said the diplomat, close to the Vienna-based International Atomic Energy Agency.
"What they are not doing is building a stockpile of enriched uranium that would give them a bomb breakout ability, something like 100-200 kg (240-480 pounds). It is just a few grams here, a few grams there," he said.
There was no immediate comment on the centrifuges from Iran, but President Mahmoud Ahmadinejad said on Monday that Western powers were wrong if they thought his country would retreat under political pressure from its nuclear plans.
In Washington, State Department spokesman Sean McCormack said he was unable to confirm the action, but said Washington feared Iran was moving towards large-scale production.
"That would be something that would be quite alarming for the rest of the world because that means that you are able to start to produce -- or at least have the capability to produce -- large amounts of highly-enriched uranium which lead you to the building blocks for a nuclear weapon," he told reporters.
The Islamic Republic says it wants to enrich uranium only to generate electricity. The West suspects that OPEC's No. 2 oil exporter is trying to build bombs under the guise of a civilian programme to threaten Israel and Western interests.
Diplomats said Iran could have fired up the second cascade at Natanz in central Iran months ago but may have decided to do so now only after the recent collapse of talks with the European Union to explore a compromise on enrichment that could avert UN sanctions.
SECOND CASCADE
"The message of the second cascade seems to be: 'Talks have broken down and we are not going to suspend'" as the precondition for negotiations to implement trade incentives offered by six world powers, said the first diplomat.
"IAEA inspectors have not seen Iran enriching (recently), but they had been on the verge of starting the second cascade for quite some time," said a second senior diplomat.
While Iran had processed enough uranium ore to inject large amounts into centrifuges, and proven it could enrich to the benchmark 5 percent level for power-plant fuel, it seemed to be holding back to avoid alienating Russia and China.
Iran counts on Moscow and Beijing, both major trade partners and Security Council veto holders, to prevent the United States from pushing through anything more than largely symbolic sanctions.
France, Britain and Germany are drafting an initial Security Council sanctions resolution likely to target only imports that could be used for nuclear work. Iran's programme has been largely based on smuggled technology for years.
Diplomats in the EU, which Iranian officials have threatened with unspecified penalties if sanctions are enacted, fear a tough resolution now could boost Ahmadinejad domestically.
Western intelligence experts estimate Iran remains 3-10 years away from an industrial-scale operation of thousands of centrifuges that could yield enough fuel for nuclear bombs.
IAEA chief Mohamed ElBaradei has suggested the West has time to do more to find a face-saving compromise with Iran.
This could entail giving Iran incentives, such as security guarantees, to rely only on imported enriched uranium for atomic energy, thereby not mastering the critical technology at home.
ElBaradei fears Iran could make good on veiled threats to cripple IAEA inspections if slapped with sanctions.
"The IAEA fully expects the Iranians to limit the scope and access of inspector visits, for example by withholding visas, if this (pending) resolution passes," one senior diplomat said.