With an announcement set to take place on Sunday evening, English, Spanish and Italian sides are said to have signed up with German and French clubs not involved.
Manchester City, Tottenham and Arsenal are said to have been in talks, with the Premier League stating that they “condemns any proposal that attacks the principles of open competition and sporting merit’.
According to French outlet RMCsport, there will be only English, Spanish and Italian clubs involved in the initial announcement – and they could face sanctions down the line.
The clubs named are United, Liverpool, City, Arsenal, Chelsea, Tottenham, Barcelona, Real Madrid, Atletico Madrid, Inter Milan, AC Milan and Juventus.
The Super League is seen as a direct challenge to UEFA, who are planning to announce a new format to the Champions League to begin in 2024.
The Times had initially reported the involvement of five English clubs without City, with European Club Association chairman and Juventus president Andrea Agnelli leading plans.