The National Consumer Agency (NCA) is contacting the Irish Daily Mail today over the publication of its paper yesterday with the Sunday Tribune masthead.
Some 25,000 'special editions' of the Irish Mail on Sunday yesterday were mocked up to resemble the in-trouble Tribune.
A receiver was appointed to the Tribune last week and the paper did not publish an edition yesterday.
Its editor Noirín Hegarty in a statement yesterday blasted what she called the "shameless" action by the Mail.
The Daily Mail has however defended what it called a "marketing" exercise.
The NCA said it is considering a prosecution for breach of the Consumer Protection Act, and as a result will be making no further comment.