Players at the 12 clubs setting up their own Super League could be banned from this year’s European Championship and next year’s World Cup, UEFA President Aleksander Ceferin said Monday.

Ceferin spoke following a UEFA executive committee meeting held only hours after the English, Italian and Spanish clubs announced the project that threatens to split European soccer.

“They will not be able to represent their national teams at any matches,” Ceferin said. “UEFA and the footballing world stand united against the disgraceful self-serving proposal we have seen in last 24 hours from a select few clubs in Europe that are fueled purely by greed above all else.”

UEFA’s 55 member federations are gathering for an annual meeting on Tuesday, including 24 nations that are playing in Euro 2020.

“My opinion is that as soon as possible they (the clubs) have to be banned from all our competitions, and the players from all our competitions,” Ceferin said.

Three of the 12 rebels — Chelsea, Manchester City and Real Madrid — are scheduled to play in the Champions League semifinals this month.

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Earlier, the 12 clubs planning to start the breakaway Super League told the leaders of FIFA and UEFA that they have begun legal action aimed at fending off threats to block the competition.

The letter was sent by the group to Ceferin and FIFA President Gianni Infantino saying the Super League has already been underwritten by funding of 4 billion euros ($5.5 billion) from American bank JPMorgan Chase.

Currently, teams have to qualify each year for the Champions League through their domestic leagues, but the Super League would lock in 15 places every season for the founding members. The seismic move to shake up the sport is partly engineered by the American owners of Arsenal, Liverpool and Manchester United, who also run franchises in closed U.S. leagues — a model they are trying to replicate in Europe.

UEFA warned the Super League clubs, including Barcelona, Real Madrid and Juventus, that legal action would be taken against them and said they also would be barred from existing domestic competitions like the Spanish league and the Premier League.

“We are concerned that FIFA and UEFA may respond to this invitation letter by seeking to take punitive measures to exclude any participating club or player from their respective competitions,” the Super League clubs wrote to Infantino and Ceferin in a letter obtained by The Associated Press.

“Your formal statement does, however, compel us to take protective steps to secure ourselves against such an adverse reaction, which would not only jeopardize the funding commitment under the Grant but, significantly, would be unlawful. For this reason, SLCo (Super League Company) has filed a motion before the relevant courts in order to ensure the seamless establishment and operation of the Competition in accordance with applicable laws.”

The courts were not named.

“It is our duty, as SLCo’s board members, to ensure that all reasonable actions available to protect the interests of the Competition and our stakeholders are duly taken, given the irreparable damage that would be suffered if, for any reason, we were deprived of the opportunity to form promptly the Competition and distribute the proceeds of the Grant,” the Super League letter continued.

The Super League intends to launch a 20-team competition with 15 founding members but only 12 have currently signed up. The others are Arsenal, Chelsea, Liverpool, Manchester City and Tottenham from England, Atletico Madrid from Spain, and AC Milan and Inter Milan from Italy.

The breakaway was launched just as UEFA thought it had agreement on an expansion of the Champions League from 2024. Now, the same officials who backed the plans have decided to go it alone while claiming the existing competitions could remain — despite losing their most successful teams, including record 13-time European champion Real Madrid and six-time winner Liverpool.

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“The Competition is to be played alongside existing domestic league and cup competitions, which are a key part of European football’s competitive fabric,” reads the Super League letter to Infantino and Ceferin. “We do not seek to replace the UEFA’s Champions League or the Europa League but to compete with and exist alongside those tournaments.”