The Football League is investigating Liverpool to find out if the Premier League club potentially fielded an ineligible player in its third-round League Cup victory over MK Dons on Wednesday.
Possible sanctions could include a fine or Liverpool being removed from the competition. The identity of the player in question was not disclosed.
“We are currently considering the matter,” an EFL spokesman said.
“The club are aware of a potential administrative issue pertaining to one of our players,” a Liverpool spokesman 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.”