UEFA president Alexander Ceferin has promised to punish participants in the Super League and says that any players involved "will be banned from the World Cup and Euros".
The announcement of a new European competition that would see a number of top clubs break away from the Champions League has been met with fierce opposition over the past 24 hours.
UEFA has now revealed its stance, with Ceferin calling for the football world to rally against the "cynical plan" that is threatening to cause huge division across the continent's major leagues.
What has been said?
"I cannot stress more strongly how everyone is united against these disgraceful, self-serving proposals, fuelled by greed above all else," the UEFA president said while unveiling the new Champions League format that is set to come into effect in 2024.
"We are all united against this nonsense of a project. Cynical plan, completely against what football should be. We cannot and will not allow that to change.
"Players who will play in the teams that might play in the closed league will be banned from the World Cup and Euros. We urge everyone to stand tall with us as we do everything in our power to ensure this never ends up in fruition."
Asked if the Champions League will continue without the 12 clubs reportedly founding the Super League, Ceferin responded: "Yes, of course. In Europe, there are many good clubs and devoted fans. You heard the changes already today of the UEFA changes from 2024. We will do it with or without them."
How does the Super League threaten the Champions League?
The Super League's formation has been designed to challenge the UEFA Champions League as the biggest competition in European football.
All of the clubs that agree to join have been promised a $450 million signing up bonus, with Manchester United, Manchester City, Arsenal, Chelsea, Liverpool and Tottenham slated to represent the Premier League in the new competition.
Real Madrid, Barcelona, Atletico Madrid, Juventus, Inter and AC Milan have also pledged to take part, which would significantly reduce the level of competition in the Champions League.
Madrid have lifted more European Cups than any other team, with 13, while Milan have won the competition seven times, Liverpool have triumphed six times, Barca have won it on five occasions and Manchester United and Inter have won three each.
Juventus have also been victorious in Europe twice, while Chelsea have one continental success to their name.
Who has opted out of the Super League?
Not every major European club is on board with the Super League, with Borussia Dortmund and Porto having already confirmed that they will not be breaking away from the Champions League.
Bayern Munich and Paris Saint-Germain are reportedly taking the same stance, with the new competition slated to have a total of 20 participants including three extra founders and five qualifiers based on performance criteria.