Boris Johnson has said the government will do everything it can to make sure the new European Super League “doesn’t go ahead in the way that it’s currently being proposed”, calling the plans "very damaging for football".
The prime minister said he would work with football authorities opposed to the move, adding: "I don’t think that it’s good news for fans, I don’t think it’s good news for football in this country."
He said: "These clubs are not just great global brands – of course they’re great global brands – they’re also clubs that have originated historically from their towns, from their cities, from their local communities, they should have a link with those fans, and with the fan base in their community."
Mr Johnson said the six Premier League clubs involved "must answer to their fans" before deciding to launch the breakaway competition.
Twelve of Europe’s leading football clubs have agreed to establish the Super League, despite widespread criticism of the plans from fans, former players, managers and governing bodies, who have warned it will "devalue" existing club leagues and competitions and have a devastating impact on grassroots football.
A statement from the new competition said: "AC Milan, Arsenal, Atletico Madrid, Chelsea, Barcelona, Inter Milan, Juventus, Liverpool, Manchester City, Manchester United, Real Madrid and Tottenham Hotspur have all joined as founding clubs.
"It is anticipated that a further three clubs will join ahead of the inaugural season, which is intended to commence as soon as practicable."
Florentino Perez, president of Real Madrid and the first chairman of the European Super League, said: "We will help football at every level and take it to its rightful place in the world.
"Football is the only global sport in the world with more than four billion fans and our responsibility as big clubs is to respond to their desires."
The project is being launched to rival UEFA’s Champions League format which currently dominates European football – and the announcement came a day before UEFA was due to sign off on plans for an expanded and restructured tournament.
The Super League has also been criticised by Labour Party leader Sir Keir Starmer, who said the plans had ignored the fans – and urged a rethink.
He said: "Football in empty stadiums hasn’t been the same over the last year. I can’t wait to get back to games. But this proposal risks shutting the door on fans for good, reducing them to mere spectators and consumers.
"The clubs involved in this proposal should rethink immediately. And if they don’t, they should face the consequences of their actions. Because football without fans is nothing."
Manchester United defender Gary Neville told Sky Sports: "I’m not against the modernisation of football competitions, we have the Premier League, the Champions League, but I think to bring forward proposals in the midst of COVID and the economic crisis for all clubs is an absolute scandal.
"United and the rest of the ‘Big Six’ that have signed up to it against the rest of the Premier League should be ashamed of themselves."
He added: "They should deduct six points off all six teams that have signed up to it. Deduct points off them all. To do it during a season? It’s a joke."
UEFA, the FA and the Premier League are among others to have expressed opposition, saying in a joint statement that they "remain united in our efforts to stop this cynical project", adding: "We thank those clubs in other countries, especially the French and German clubs, who have refused to sign up to this.
"This persistent self-interest of a few has been going on for too long. Enough is enough."
The English FA said: "We would not provide permission to any competition that would be damaging to English football, and will take any legal and/or regulatory action necessary to protect the broader interests of the game."
Measures, both judicial and sporting, are being considered by the football authorities to stop the competition.
This could include attempts to bar the competing clubs from domestic leagues and their players from international competitions too.
World governing body FIFA has called for "calm, constructive dialogue" to resolve the crisis, which it is feared could develop into a long, complex, expensive and divisive legal battle between football authorities and the breakaway group.
The European Super League competition will see 20 participating clubs – 15 founding clubs and a further five teams able to qualify annually based on their achievements during the previous season.
Malcolm Clarke, chair of the Football Supporters Association, told Sky News he is yet to speak to a fan who is in favour of the move.
"We are totally opposed to it… the supporters’ organisations at these so-called big clubs have all come out against it. As far as I can see, everybody who cares about it and respects the tradition of English football is against this."
Asked why he thought this was happening if opposed by the fans, he replied: "Money. Simple as that isn’t it. You have only got to look at the eye-watering amounts of money that they think they are going to earn out of this.
"These are foreign owners who are basically asset managers who can see a way of making massive amounts of money out of this. They are not people who are custodians of the sporting heritage of this country. If they were, they wouldn’t be proposing this."
He said he "absolutely" supported calls for the six English clubs to be removed from the Premier League, adding he and colleagues would be asking the FA Council to support a resolution to that effect this week.
"We are geared up for this fight, and it is absolutely essential that the Premier League, the Football Association and the supporters of all of those clubs stick together."
He added he wasn’t expecting many players, if any, to speak out publicly against the creation of the breakaway league, but if they voiced their opposition behind the scenes it may act as a deterrent within the clubs themselves "if they think that some of the top players might not sign for them in the future because they want to pursue their international careers".
The super league will begin in August with clubs participating in two groups of 10, playing home and away fixtures, some during the week, with the top three in each group qualifying for the quarter-finals.
Teams finishing fourth and fifth will compete in a two-legged play-off for the remaining quarter-final spots before a knockout format is used to reach the final at the end of May, which will be staged as a single fixture at a neutral venue.
In exchange for their commitment, founding clubs will receive an amount of €3.5bn (£3bn) to "support their infrastructure investment plans and to offset the impact of the COVID pandemic", the league’s statement said.
Club players will be able to continue competing in their national leagues and, as soon as possible after the men’s competition begins, a women’s league will also be launched.