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?