In their High Court action, Hull claim that a company linked to Duffen received payments from agencies who were given a lot of work by the club, as well as alleging that Duffen used club money for personal expenses.
Duffen has denied the allegations but discussions continue between lawyers for both parties in an effort to resolve the issue.
Investigation: Ex-Hull City chariman Paul Duffen (left), here in talks with Phil Brown
The Football Association have been kept fully informed by the club and will pursue any allegations of wrongdoing.
An FA spokesman said: 'We have been in contact with the club.'
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