The Football League has ruled that Italian businessman Massimo Cellino cannot take over Leeds United.
Cellino failed the League's Owners' and Directors' Test because of a recent conviction in an Italian court.
A statement from the Football League read: "At its meeting yesterday evening (Sunday), the Board of The Football League considered the eligibility of Massimo Cellino under its Owners' and Directors' Test.
"The Board considered detailed legal advice with regard to the application of its regulations within the context of a decision made under Italian law.
"Mr Cellino was recently found guilty beyond reasonable doubt by a Court in Sardinia of an offence under Italian tax legislation relating to the non-payment of import duties on a boat. This resulted in a fine of €600,000, an order for the payment of trial costs and the confiscation of the boat in question.
"Having fully considered the matter, the Board agreed unanimously that the decision of the Italian Court does constitute a disqualifying condition under its Owners' and Directors' Test.
"The relevant disqualifying condition being that Massimo Cellino has been convicted of an offence involving acts that would reasonably be considered to be dishonest.
"In line with Football League regulations, Massimo Cellino is entitled to appeal against the Board's decision within 14 days. In such circumstances, The League would seek to expedite the process to deliver certainty to all parties in the shortest possible timeframe."
Leeds responded by saying they are "disappointed" by the decision.
"The club and its shareholders are disappointed at the decision of the Football League not to approve Massimo Cellino as a director of Leeds United FC.
"However, the Board and Executive Management of the club, will continue discussions with the Football League and Eleonora Sport to find a solution that is suitable to all parties.
"Our shareholders continue to support the club directly or through additional investments as has always been the case.
"We would like to reassure the fans of the continuity of our great club."
Cellino has previously suggested that he would not contest the League's decision, despite him appealing the ruling of the Italian court and his lawyer arguing that he should be viewed as innocent until that final sentence is passed.
The League's rejection of Cellino is the latest development in what has been a protracted and often chaotic series of events surrounding the Italian's proposed takeover of the club.
Cellino was reported to be pivotal in the decision to sack Brian McDermott with two hours of the last January transfer window remaining, despite him not having yet finalised a deal to buy a 75% stake in the club.
McDermott was reinstated as manager a day later, with Cellino denying that he was responsible for sacking him and suggesting he was looking forward to forging an effective working relationship with the former Reading boss.
Since then, the club have suffered a dip in form, which saw them win just two of 16 games before Saturday's 2-1 home win over Millwall, a run which promoted McDermott to demand a resolution to the club's "de-stabilising" off-the-field affairs.
Bahrain-based investment bank GFH recently wrote to the Football League to attack what they perceived to be an "unprecedented delay" in deciding on Cellino's take-over.
With the Cellino deal now having being rejected, the future of Leeds is again in doubt, although managing director David Haigh recently said there was "no chance" the club would go into administration.