The 12 founding members of the European Super League (ESL) – including the "big six" English clubs – have resigned from the European Club Association (ECA).
The ECA is the body which represents all professional clubs in Uefa, and the only one Uefa recognises.
It has said it is "strongly opposed" to the new league, and held an emergency meeting on Sunday after news of its creation broke.
Representatives from the Super League clubs did not attend.
This includes Juventus chairman Andrea Agnelli, who was chairman of the ECA but has resigned from his position.
What is the ECA?
The ECA was formed in 2008 to replace the G-14, which comprised only a small number of elite clubs and was not recognised by Uefa.
Its mission statement is "to create a new, more democratic governance model that truly reflects the key role of the clubs".
The association has 232 member clubs, with at least one from each of Uefa's 54 national associations.
It gives clubs greater influence in decision-making at Uefa, with ECA representatives from the executive board are sitting on the Uefa Executive Committee, Uefa Club Competitions Committee, Uefa Professional Football Strategy Council and the Uefa Women's Football Committee.
ESL founding members England ArsenalChelseaLiverpoolManchester CityManchester United
Tottenham Italy AC MilanInter Milan
Juventus Spain Atletico MadridBarcelona
Real Madrid "It is anticipated that a further three clubs will join ahead of the inaugural season," the league said.
Bayern Munich and Paris Saint-Germain have so far insisted they have not signed up.
Response to ESL
The ECA released the following statement on Sunday: "In light of today's reports on the subject of a so-called breakaway league, ECA as the body representing 246 leading clubs across Europe, reiterates its stated commitment to working on developing the Uefa club competitions (UCCs) model with UEFA for the cycle beginning 2024 and that a 'closed super league model' to which media articles refer would be strongly opposed by ECA.
"ECA would refer to the position adopted by its executive board at its meeting last Friday 16 April, namely that it supports a commitment to work with Uefa on a renewed structure for European club football as a whole post-2024.
"With ECA's support, Uefa's executive committee is being asked to endorse these commitments at its meeting on 19 April along with pursuing efforts to reach an agreement on the future relationship between ECA and Uefa.
"The ECA executive board will be convening over the coming days to take appropriate decisions in light of any further developments."
How will the ESL work?
There will be 20 teams in the competition, the 15 founding members and five others, who will qualify annually based on their domestic achievements.
It is planned to start in August with two groups of 10, with home and away fixtures played midweek.
The top three in each group would qualify for the quarter-finals, with the fourth and fifth-placed teams competing in playoffs for the final spots.
The knockout stages would be played over two legs, with the final a single fixture at a neutral venue, played in May.
"As soon as practicable after the start of the men's competition, a corresponding women's league will also be launched, helping to advance and develop the women's game," the league statement said.
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