An-ex finance worker in Jersey has claimed in a book he was a secret agent for the French equivalent of MI6.
The former fund administrator wrote that he volunteered as a spy to expose a rogue world - with systems set up to escape tax - which he described as like Russian dolls.
Maxime Renahy, 40, worked for Mourant International Finance Administration in Jersey for three years from 2007. State Street bank later bought the company.
The States of Jersey said it would not comment on the book's "unverified claims".