Proposals to expand the Champions League from season 2024-25 have been criticised by Premier League clubs.
The Premier League has released a statement claiming all 20 clubs are unanimously against proposed changes to the Champions League.
Plans for an expansion of the group stage, potentially from six to 14 games, leading to fixtures being staged at weekends, have been discussed by the European Club Association (ECA).
It has also been suggested qualification could be restricted to clubs with a history of European success, rather than by finishing in the top four of the Premier League.
In a rare move, the Premier League released a statement on Friday laying out clubs' concerns about the ECA's planned revamp for the competition.
Premier League statement
"All 20 Premier League clubs today discussed their significant concerns regarding reported proposals for changing the format and qualification criteria of UEFA club competitions from season 2024-25," said the statement.
"All clubs unanimously agreed it is inappropriate for European football bodies to create plans that would alter the structures, calendar and competitiveness of the domestic game and will work together to protect the Premier League.
"In England, football plays an important role in our culture and everyday life. Millions of fans attend matches across the country, with allegiances and local rivalries often passed down through generations.
"We have a fantastic combination of competitive football and committed fans that we will vigorously defend. The structures of domestic football are determined by leagues and their respective national associations.
"We will now work with the Football Association and other leagues to ensure that European football bodies understand the importance of this, and their obligation to maintain the health and sustainability of domestic league football."
Four Premier League clubs - Liverpool, Manchester City, Manchester United and Tottenham - are in the quarter-finals of this season's Champions League.
There is guaranteed to be at least one top-flight representative from England in the semi-finals too, as City and Spurs face each other in the last eight.