FIFA president Gianni Infantino has issued a strong warning to the 12 European Super League clubs that they will have to "live with the consequences of their choice".
The head of football’s international governing body added his weight to the growing opposition to the proposals by confirming that his organisation "strongly disapproves" of the move.
The Premier League ’s so-called ‘big six’ - Manchester City, Manchester United, Liverpool, Arsenal, Chelsea and Tottenham - are among the clubs who have confirmed their plans to create their own competition.
The proposal - also supported by Real Madrid, Atletico Madrid, Barcelona, Milan, Inter and Juventus - aims to transform the landscape of European football by offering a rival to UEFA’s Champions League.
FIFA’s opposition is the latest blow to the proposals which have also been condemned by UEFA, its member football federations, the Premier League and governments.
Infantino said during Tuesday morning’s UEFA congress: "We can only strongly disapprove the creation of the Super League, a Super League which is a closed shop, which is a breakaway from the current institutions, from the leagues, from the associations, from UEFA and from FIFA.
"There is a lot to throw away for the short-term financial gain of some. They need to reflect, and they need to assume responsibility."
The FIFA supremo then warned the 12 clubs involved: "If some elect to go their own way then they must live with the consequences of their choice. They are responsible for their choice.
"Concretely, this means either you're in or you're out. You cannot be half in or half out."
UEFA president Aleksander Ceferin also spoke at the congress to thank Infantino for his solidarity: "You showed that you care about the values of football. And if we stand together, we are unbeatable."
Ceferin also warned the English clubs on the situation and reaffirmed that it was not too late for them to reverse their plans: "Gentlemen, you made a huge mistake.
"What matters is that there is still time to change your mind. Everyone makes mistakes.
"Come to your senses, not out of love for football, because I imagine some of you don't have much of that, but out of respect for those who bleed themselves dry so that they can go to the stadium to support the team and want the dream to be kept alive. For those, you (must) change your mind."
"Where were Manchester United in the decade before Sir Alex Ferguson arrived on the scene? And where were Juventus 15 years ago?"
The next steps remain unclear as a tangible split emerges at the top end of European football.
