The club had a Luis Diaz goal ruled out in north London due to miscommunication between VAR Darren England and on-field referee Simon Hooper. The Premier League game was goalless at the time of the incident, with the Reds going on to lose 2-1.
PA understands the Reds have now formally requested the audio of the conversation between the two from referees' body Professional Game Match Officials Limited (PGMOL).
Liverpool issued a statement on Sunday night saying they would “explore the range of options available given the clear need for escalation and resolution”.
Much of the focus since has been on precisely how the club would like the matter escalated and resolved, and their first step has been to seek access to precisely what England and Hooper said to each other which led to the mistake.
PGMOL issued a statement on Saturday night acknowledging a “significant error” had occurred. Hooper and his assistants had given offside against Diaz on the field, and the PA news agency understands that although England followed the correct procedure in drawing lines, he lost focus and mistakenly thought the initial on-field decision had been onside.
This resulted in him issuing a ‘check complete’ notice to Hooper, rather than advising of an intervention and the goal being awarded.
Once the officials realised an error had been made, play had restarted and VAR protocols state that once that has happened, there is no way back to revisit a decision.
England was replaced as a fourth official for the Nottingham Forest v Brentford match on Sunday while his assistant VAR at Tottenham, Dan Cook, has been replaced for Monday night's match between Fulham and Chelsea.
Referee and VAR appointments for the coming weekend's matches are due to be announced at 10am on Tuesday morning.
The controversy over the Diaz goal has led to calls for the conversation between England and Hooper to be broadcast. PGMOL has not ruled out the possibility of the audio forming part of the next 'Match Officials Mic'd Up' programme, which is due to air next Monday.
England and Cook had been part of a team of officials who oversaw a fixture between Sharjah and Al Ain in the United Arab Emirates on Thursday, arriving back in the UK on Friday morning.
Requests for English officials to take charge of domestic matches overseas are made to the Football Association, with permission for officials to travel granted jointly by the FA and PGMOL.
Just as players involved in Europa League matches on a Thursday do not return to domestic action until Sunday, so officials' duties are balanced to take account of any overseas assignments in the week. For instance, Michael Oliver, who refereed the match in the UAE last week, was a fourth official on Saturday but was back to refereeing at Forest on Sunday.
Nor was the UAE trip unusual. It was the fifth time in the last 10 months that officials have overseen domestic matches overseas, with Tom Bramall and Andy Madley leading teams to Japan in January and the early summer respectively, Oliver officiating a Saudi match in April and Craig Pawson going to Greece in May.
That is on top of English officials frequently being called upon for club and national team matches in international competitions.
Liverpool's statement said the error that occurred had led to sporting integrity being undermined, but Manchester United manager Erik ten Hag said on Monday he still had complete “trust” in referees.
“Well, I'm not so often giving comment on refereeing because they do what they have to do,” the Dutchman said.
“Of course, the standard has to be high and it's a part of the game. Of course, you can expect, we can expect, teams can expect, the fans can all expect, that it has to be a high standard - so it should be because it's Premier League.
“But I think and I'm sure they do what they can. They are very professional, so they will give their best and I trust them.”