The European Super League (ESL) is a “disgraceful, self-serving” proposal and a “spit in the face of all football lovers”, says Uefa president Aleksander Ceferin.
Arsenal, Chelsea, Liverpool, Manchester City, Manchester United and Tottenham are among 12 clubs who have agreed to join a new ESL.
It has been met with condemnation by Fifa and Uefa, Europe’s football governing body.
It is a “nonsense”, Ceferin added.
“I cannot stress more strongly how everyone is united against these disgraceful, self-serving proposals, fuelled by greed above all else,” he said.
“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.”
He added: “This idea is a spit in the face of all football lovers. We will not allow them to take it away from us.”