As Iran defies the world by restarting its nuclear programme, Paul Kenyon travels to the Islamic Republic with UN nuclear inspectors, and gains exclusive behind-the-scene access to the International Atomic Energy Agency.
Iranian negotiators talk candidly about why they deceived the world over their nuclear programme for 18 years.
The diplomatic to-ing and fro-ing covered in the programme was filmed in the first six months of this year.
But it takes on a new complexion now we know that Iran later abandoned the diplomacy and chose to start enriching uranium again.
First shown in May of this year, the programme has been updated with the latest events.
Iran's Nuclear Secrets was broadcast on Tuesday, 23 August, 2005 at 2320 BST on BBC Two.
Producer/director: Paul Kenyon
Executive producer: Karen O'Connor