The VAR audio that led to Liverpool's goal wrongly being disallowed in a defeat to Tottenham has been released - with the refereeing body admitting standards "fell short of expectations".
Luiz Diaz's goal on Saturday was ruled out for offside on the field, which was upheld after a review even though replays showed the Colombian forward was clearly onside.
This came despite the VAR team acknowledging Diaz was onside in a mix-up that led to them believing the on-field call was to award a goal.
In the audio, it takes about 30 seconds for VAR Darren England and his assistant Daniel Cook to judge Diaz was onside.
Not realising the linesman had raised his flag for offside, the VAR said: "Check complete, check complete. That's fine, perfect."
When the replay operator points out the on-field decision was to rule the goal out for offside, it takes a few seconds for the team to understand.
"Oli's calling to delay the game," the replay operator said, referring to Oli Kohout, VAR hub operations executive at the PGMOL.
The VAR is heard swearing in the audio, before saying they "can't do anything" as they've "restarted the game".
The Professional Game Match Officials Limited (PGMOL) said in a statement "standards fell short of expectations" and it has identified three key learnings "to mitigate against the risk of a future error".
On Sunday, Liverpool said they would explore their options given the "clear need for escalation and resolution".
PGMOL will stress the importance of accuracy to its video match officials, while a "new VAR communication protocol will be developed to enhance the clarity of communication between the referee and the VAR team in relation to on-field decisions".
The group added: "As an additional step to the process, the VAR will confirm the outcome of the VAR check process with the AVAR before confirming the final decision to the on-field officials.
"We recognise standards fell short of expectations and acknowledged the error to Liverpool immediately after the conclusion of the fixture."
England and Cook have not been included among the officials for duty in the coming weekend's Premier League fixtures.
A Premier League spokesperson said "it is clear that there were not only human errors but systemic weaknesses in the VAR process".
"We accept PGMOL's immediate recommendations to ensure that such failures are not repeated in the future," they added.
"However, a wider review to seek consistently higher standards of VAR performance will be conducted by the Premier League and PGMOL, supported by other stakeholders, and where necessary further recommended actions will be brought forward and implemented.
"We have communicated fully with Liverpool FC on this matter and have shared PGMOL's findings and relevant footage of the incident with all Premier League clubs."