By Francois Murphy
VIENNA (Reuters) - Iran's barring of some of the U.N. nuclear watchdog's most experienced and expert inspectors from the team allowed to operate there is a "very serious blow" to the agency's work, the watchdog's chief Rafael Grossi said on Wednesday.
Tehran informed the International Atomic Energy Agency in September that it was taking the step, known as de-designation. The IAEA said at the time that while Iran is allowed to do that, the way it was done was unprecedented and harmful to its work.
"It's a very serious blow to our capacity to do that," Grossi told a news conference when asked to what extent the move had affected the IAEA's ability to carry out meaningful inspections in Iran. He is urging Tehran to reconsider.
Uranium enrichment is the heart of Iran's nuclear programme, and the process by which uranium is purified to levels as high as 60%, close to the roughly 90% that is weapons-grade. Iran denies seeking nuclear weapons but no other state has enriched to that level without producing them.
The IAEA will not say how many inspectors were de-designated. Diplomats put the number at slightly more than a handful. While that is a fraction of the more than 100 inspectors assigned to Iran, they are among the IAEA's top experts on uranium enrichment, officials said.
One diplomat put the number of inspectors barred in this wave at eight, all of them French and German. That left only one enrichment expert in the team assigned to Iran, they added.
One senior diplomat put the number of other enrichment experts available with the required know-how at probably fewer than five.
"There are not many countries with this type of expertise. And normally countries where this expertise exists are very reluctant to release the expertise. They also were inspectors that were familiar with the facilities, had been there for years inspecting the facilities," the senior diplomat said, referring to the de-designated inspectors.
The importance of that experience was illustrated in January when an inspector noticed a subtle but substantial change to a cascade, or cluster, of uranium-enriching centrifuges that Iran had failed to inform the IAEA of. That change caused a spike in the enrichment level to 83.7%, a record.
The inspector who spotted that change, a Russian enrichment expert, was de-designated later this year, shortly before the others, numerous diplomats said.