If the IAEA is alarmed......

then everybody should really be worried....

Inspectors from the UN atomic watchdog are "alarmed" that Iran has in its possession a document describing the process for making what could be the core of a nuclear weapon, a western diplomat said Thursday.

And at a closed-door meeting with diplomats, the International Atomic Energy Agency's chief for inspections, Olli Heinonen, revealed that the agency had gathered intelligence from around 10 countries suggesting Iran was engaged in weaponisation studies in the past, the diplomat said.

Tehran has repeatedly dismissed the intelligence as "fabricated," and the allegations that it was seeking to build a bomb as "baseless".

At a briefing to prepare IAEA board members for a meeting of the full board next week, Heinonen talked about the so-called uranium metal document, the diplomat said on condition of anonymity.

The 15-page document describes the process of machining uranium metal into two hemispheres of the kind used in nuclear warheads.

"And the term he used for this document was 'alarming'. He essentially said there was no reason why a country would need to possess such a document unless they wanted to produce uranium hemispheres for a nuclear weapon," the diplomat said.