Johnson completed an £11m takeover of Everton in July 1994 but the Football League has discovered he retained an interest in First Division Tranmere.

Now Johnson must relinquish his interests in one of the clubs by the end of the year or the Football League and the Premier League will launch an investigation into the situation.

That investigation will establish whether Johnson's interests in both clubs amounts to a breach of Football League and Premier League regulations in terms of multi-ownership.

Football League chief executive Richard Scudamore said: "When we became aware that Mr Johnson had an interest in Tranmere as well as Everton we gave limited consent for the situation to exist for a further 90 days in order to effect a quick disposal of interest in one of the clubs.

"Mr Johnson intimated that it would be Tranmere and we have sought to protect the interests of Tranmere in keeping the club alive.

"After December 31 it will be the responsibility of the Football League and the Premier League to examine jointly the entire situation to ascertain any breaches of regulations and determine what action should be taken."

Premier League spokesman Mike Lee ruled out the possibility of any action being taken against Johnson.

He said: "There is no question of any disciplinary action against Everton FC.

"The Premier League were informed by the Everton Chairman of the situation on 30th September and the matter was discussed jointly with the Football League.

"It was agreed that Mr Johnson would have until December 31 to clarify the situation or divest his interests in one of the clubs concerned.