Liverpool have asked PGMOL for audio of the conversation between match officials and the VAR about Luis Diaz's disallowed goal in their 2-1 loss at Tottenham Hotspur.
The Reds were controversially denied the opening goal of the game when Diaz's strike was ruled out for offside. But replays clearly showed he was being played onside by Cristian Romero and the strike should have been allowed to stand.
It has since been explained that VAR Darren England believed the goal had in fact been given by the on-field officials and his check was to see whether this was the correct call. He informed referee Simon Hooper that this check was complete, thinking the game would restart with a Spurs kick-off following the awarding of a goal.
However, it instead began again with Tottenham taking a free-kick for the offside call and the game remained at 0-0. Once play has restarted, a decision cannot retrospectively be changed.
PGMOL quickly recognised post-match this decision was erroneous and put it down to 'significant human error'.
- LISTEN TO THE LATEST EPISODE OF 90MIN'S TALKING TRANSFERS PODCAST: IVAN TONEY, SON HEUNG-MIN, BRUNO GUIMARAES & MORE
Liverpool have now formally requested to hear the audio from the discussions between Hooper and England regarding the disallowed goal.
The Reds released a statement on Sunday night in which they claimed they would "explore the range of options available, given the clear need for escalation and resolution."
This loss saw Liverpool's 19-match unbeaten run - stretching back to last season - come to an end.
Jurgen Klopp's side nearly held on to claim a point at Tottenham Hotspur Stadium, only for Joel Matip to divert the ball into his own net from a Pedro Porro cross in the 96th minute.
Meanwhile, Liverpool will lodge an appeal against the red card shown to Curtis Jones shortly prior to Diaz's disallowed goal. The midfielder was sent off following a VAR review for a dangerous challenge on Yves Bissouma.