Anti-Lisbon Treaty campaigner Declan Ganley has said he will sue RTÉ over last Thursday's Prime Time programme about his business activities.
Watch the Prime Time profile of Declan Ganley
In a statement, the Libertas chairman said his legal advice was that the programme was actionable.
A file is being prepared for what Mr Ganley said would be a significant and extensive legal action against RTÉ and Prime Time.
RTÉ has said it has not had any contact from Mr Ganley or Libertas in relation to the matter and so was unable to comment at this time.
The station said Prime Time fully stood over the programme as broadcast.