Top European clubs have allegedly held secret talks to create a European Super League, according to a report by German publication Der Spiegel.
The newspaper claims leaked documents show the breakaway league could be created in 2021 and see clubs involved leave their national leagues and football associations.
Der Spiegel says its source is a whistleblower they call John, who claims that neither he nor his associates are hackers: "We have very good sources and a strong network that provides us with a lot of information," he told Der Spiegel.
The German newspaper claims Real Madrid has joined forces with AC Milan, Arsenal, Barcelona, Bayern Munich, Juventus and Manchester United to form a group of seven sides who went behind the back of Uefa, European football's governing body, to discuss forming a European Super League.
As part of their plans, the clubs allegedly discussed "an option for leaving the national leagues and their football associations behind entirely".
Bayern Munich are supposed to have explored the legal complexities of the breakaway and one of the documents Der Spiegel says it has seen is a "binding term sheet" which 16 clubs would sign to form the Super League.
The new competition, it is claimed, would involve 11 of Europe's biggest clubs, known as the "founders", along with five "initial guests".
The so-called founders, who would include the seven clubs named above along with Chelsea, Liverpool, Manchester City and Paris St-Germain, would not face relegation and would be guaranteed membership for 20 years.
Der Spiegel reports that the five "initial guests", according to the document, would be Atletico Madrid, Borussia Dortmund, Inter Milan, Marseille and Roma.
A Bayern Munich statement said they were "unaware of recent plans for a so-called Super League" and had not "taken part in negotiations relating to such plans".
The club's chairman added: "FC Bayern Munich stands by its membership of the Bundesliga and, as long as I am chairman of the board of FC Bayern, also by the club competitions organised jointly by Uefa and the ECA (European Club Association)."
United declined to comment, while Arsenal, AC Milan, Juventus and Real Madrid, contacted for their response by BBC Sport, had not replied at the time of going to press.
Der Spiegel says the source of the documents they have obtained is a whistleblower called John, which is not his real name, who founded Football Leaks.
Up to 70-million documents have been provided by Football Leaks and more than 3.4 terabytes of information.
Der Spiegel has shared the information with other media outlets in the European Investigative Collaborations consortium, which includes the Reuters news agency, the Sunday Times in the United Kingdom and Spain's El Mundo.
Together, about 80 journalists from 15 media outlets looked at the information provided...