The Premier League (PL) has an intention to draft a new rule to stop future attempts to join a breakaway Super League.
It follows Manchester United, Chelsea, Liverpool, Arsenal, Manchester City and Tottenham agreeing to join the failed European Super League last month.
“The Football Association said an inquiry into the six clubs has started,” it added.
“The actions of a few clubs cannot be allowed to create such division and disruption,” the Premier League said. “We are determined to establish the truth of what happened and hold those clubs accountable for their decisions and actions.”
The Football Association added: “We wrote to all of the clubs to formally request all relevant information and evidence regarding their participation.
“Once we have the required information, we will consider what appropriate steps to take.”