Liverpool risk expulsion from the Carabao Cup if they are found to have fielded an ineligible player against MK Dons on Wednesday.
The EFL is investigating the third-round win, in which Liverpool fielded four teenagers in the starting line-up.
"The club are aware of a potential administrative issue pertaining to one of our players," a club statement said.
"We are working with the relevant authorities in order to establish the facts of the matter and will be making no further comment until this process is complete."
The EFL added: "We are currently considering the matter."
The identity of the player in question has not been disclosed.