A proposed European 'Super League' that has garnered support from some of the continent's top clubs is a "cynical project" that is "founded on the self-interest of a few" according to a scathing joint statement released by UEFA and football authorites in England, Spain and Italy.
Reports today have suggested that an announcement on a breakway competition could be imminent.
Premier League sides Manchester United, Liverpool, Arsenal, Chelsea and Tottenham are among 11 clubs believed to have signed up to the plan, with Manchester City also on the verge of doing so.
Real Madrid, Barcelona and Atletico Madrid from Spain and Serie A's Juventus, AC Milan and Inter Milan are also thought to be on board but last year's Champions League finalists Bayern Munich and Paris Saint-Germain have so far declined.
Reports in January suggested 20 clubs – 15 permanent founding members and five other clubs, who would qualify on an annual basis – would be offered over €300 million each per year to join the competition.
The format would see two groups of 10 clubs who play home and away, with the top four from each group going through to two-legged quarter-finals, semi-finals and a one-legged final.
Matches would be midweek and clubs would still play in domestic leagues and have rights to show four matches a season on their own digital platforms across the world.
A statement from the European Club Association, which represents 246 clubs in Europe and is, somewhat ironically, chaired by Juventus president Andrea Agnelli, reaffirmed the organisation's committment to working with UEFA to reform its competitions and said it was "strongly opposed" to a "closed super league model".
The Premier League said it "condemns any proposal that attacks the principles of open competition and sporting merit which are at the heart of the domestic and European football pyramid.
"Fans of any club in England and across Europe can currently dream that their team may climb to the top and play against the best.
"We believe that the concept of a European Super League would destroy this dream."
UEFA statement in full
"Statement in full released by UEFA, the English Football Association, the Premier League, the Royal Spanish Football Federation (RFEF), LaLiga, the Italian Football Federation (FIGC) and Lega Serie A: UEFA, the English Football Association and the Premier League, the Royal Spanish Football Federation (RFEF) and LaLiga, and the Italian Football Federation (FIGC) and Lega Serie A have learned that a few English, Spanish and Italian clubs may be planning to announce their creation of a closed, so-called Super League.
"If this were to happen, we wish to reiterate that we - UEFA, the English FA, RFEF, FIGC, the Premier League, LaLiga, Lega Serie A, but also FIFA and all our member associations - will remain united in our efforts to stop this cynical project, a project that is founded on the self-interest of a few clubs at a time when society needs solidarity more than ever.
"We will consider all measures available to us, at all levels, both judicial and sporting in order to prevent this happening. Football is based on open competitions and sporting merit; it cannot be any other way.
"As previously announced by FIFA and the six Federations, the clubs concerned will be banned from playing in any other competition at domestic, European or world level, and their players could be denied the opportunity to represent their national teams.
"We thank those clubs in other countries, especially the French and German clubs, who have refused to sign up to this. We call on all lovers of football, supporters and politicians, to join us in fighting against such a project if it were to be announced. This persistent self-interest of a few has been going on for too long. Enough is enough."
Proposed 36-team Champions League format
The development has thrown into doubt UEFA's plan for a revamped 36-team Champions League which was to be discussed on Monday, with its executive committee expected to agree the controversial proposal.
The new format, which is set to start in 2024 and run until at least 2033, moved a step nearer on Friday following meetings between the European Club Association board and UEFA's club competitions committee.
The so-called 'Swiss model' will see teams compete in one 36-team league - instead of the current system where 32 sides are split into eight pools of four - and guarantee each club 10 matches on a seeded basis.
The new format, which guarantees clubs four more games than in the current group phase, takes the Champions League from 125 to 225 matches and would create a huge headache for domestic schedulers.
EFL chairman Rick Parry says it would be a "major threat" to the Carabao Cup and the English Football Association also wrote to UEFA to express its concerns.
Fans groups, including those from Manchester United and Arsenal, said in an open letter to ECA chairman and Juventus boss Andrea Agnelli, that the plans to restructure the Champions League "present a serious threat to the entire game".
The letter, signed by 17 fans' groups from 14 teams whose clubs are in the ECA, including Ajax, Real Madrid, Bayern Munich and Borussia Dortmund, said it was a "blatant power grab" and would "wreck domestic calendars".
The new format would see the league's top eight qualify automatically for the last-16 knockout stage, with the teams finishing ninth and 24th playing off for the remaining eight places.
Extra games would see the Champions League encroach into January - a month usually kept free for domestic club football - while the allocation of two of the extra four places to sides based on previous European performance has also proved controversial.
A team could still qualify for the Champions League based on 'historic co-efficient' as long as they did enough domestically to finish in a Europa League or Europa Conference League position.
Discussions over the commercial control of the competition are set to continue in the coming weeks.