United Nations inspectors found “nothing to be worried about” during their inspection of an underground uranium enrichment site in Iran, according to the head of the organisation’s atomic watchdog.

Mohamed ElBaradei’s assessment, the first word on what was found at the controversial site near Qom, came in the course of an interview with The New York Times to mark his imminent departure as head of the International Atomic Energy Agency.

Mr ElBaradei told the newspaper that his inspectors’ initial findings concurred with Tehran’s insistence that the plant had been built on a heavily fortified military site as a fallback in case its main plant was bombed, rather than to conceal a military use. “The idea was to use it as a bunker under the mountain to protect things,” Mr ElBaradei said.

“It’s a hole in a mountain.” Mr. ElBaradei’s words will be met with disappointment in Western capitals, long critical of his leadership of the atomic watchdog as too soft on Iran.

When Presidents Obama and Sarkozy and Gordon Brown revealed the existence of the plant in September, Mr Elbaradei conceded that Iran’s concealment had put them “on the wrong side of the law”. Western intelligence agencies said that the plant is too large to be a pilot plant and too small to produce sufficient fuel for a civilian nuclear programme, raising suspicions that it is part of a military programme towards developing a nuclear bomb.

The disclosure is credited for Iran’s seeming compliance at negotiations in Geneva on October 1 at which it agreed to allow inspectors access to the plant.

Mr ElBaradei travelled to Tehran two days later to arrange inspection and agreed to send inspectors to the plant on October 25, angering Western negotiators who believed he had given Iran too much time to clear up any incriminating evidence.

Mr ElBaradei added that the delay in reaching agreement on a uranium deal that Iran had previously agreed in principle was down to “total distrust on the part of Iran.”

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