Liverpool are seeking the match officials' audio from Saturday's 2-1 defeat at Tottenham.
The Reds have formally threatened legal action over the match's VAR management after two players were sent off and a goal was denied.
PA Sport says Liverpool have now formally requested the audio of the conversation between the two from referees' body Professional Game Match Officials Limited (PGMOL).
Liverpool want to hear the audio between VAR Darren England and on-field referee Simon Hooper which led to Luis Diaz's goal being disallowed.
PGMOL have since admitted "significant human error" led to the decisoin.