Europe’s domestic leagues have rejected current proposals for a near-closed Champions League, saying it would benefit only a few “rich and dominant clubs”.
UEFA is working with the European Club Association (ECA), whose members include all of the continent's biggest clubs, to re-design European competition after the current international calendar ends in 2024.
European Leagues - which represents 35 leagues in 28 European countries - has told UEFA to scrap its reforms and to start the project "from scratch".
The outgoing bosses of the English Football League and Premier League, Shaun Harvey and Richard Scudamore, respectively, are among the 13 men on the board.
The statement read: "The European Leagues retain the strong opinion that the presented proposal for reforming the European Club Competitions benefits just a few rich and dominant clubs but damages the leagues and the great majority of clubs playing in the domestic competitions.
"The European Leagues are working on changes which contribute to the long-term sporting and financial sustainability of both European and domestic club competitions.
"UEFA must come to an agreement with the European Leagues and the other stakeholders to safeguard the interests of all professional football clubs in Europe."
The stark message to European football's governing body emerged from a meeting of European Leagues' board of directors in Warsaw on Thursday.
Several league representatives who were present at a meeting with UEFA last week have said they were presented with a proposal to create a three-tier European league with promotion and relegation between each division.
Only four places would be open to the winners of Europe's 54 national leagues.
UEFA has said discussions are at a preliminary stage and has not given any further details.