A man from Merseyside has been arrested in connection with an investigation into the supply and sale of allegedly ineffective bomb detectors.
Avon and Somerset Police arrested the 54-year-old on suspicion of fraud by misrepresentation on Wednesday.
A BBC investigation alleged that millions of pounds worth of bomb detectors sold to Iraq did not work.
The latest arrest follows the arrest of two other men aged 54 and 42 in January and July last year.
In January 2010 Jim McCormick, 54, of ATSC Ltd, based at Sparkford, near Wincanton in Somerset, was arrested on suspicion of fraud by misrepresentation.
A 42 year-old man from Somerset was arrested in July.
Mr McCormick and the 42-year-old were released on police bail, pending further inquiries.
An Avon and Somerset Police spokesman said the investigation was "complex and prolonged".