The PGMOL have stated they are aware of the incident involving Constantine Hatzidakis and Andy Robertson and will review the matter.
A statement from the organisation, issued during the second half of the 2-2 draw at Anfield read: "PGMOL is aware of an incident involving assistant referee Constantine Hatzidakis and Liverpool defender Andrew Robertson at half-time during the Liverpool v Arsenal fixture at Anfield. We will review the matter in full once the game has concluded."
Linesman Hatzidakis was heading towards referee Paul Tierney just after he had blown the half-time whistle, carrying the ball with him. Reds star Robertson approached Hatzidakis and appeared to grab the official as he walked across the pitch.
Hatzidakis reacted angrily to that though and moved his arm back in what appeared to an elbow towards Robertson's face. The Scotland captain was left furious, with Liverpool players surrounding the trio of match officials as they attempted to leave the pitch.
Robertson, Diogo Jota and Reds skipper Jordan Henderson remonstrated with Hatzidakis and Tierney as they left the pitch. The Liverpool left-back was then booked by Tierney, to the anger of Curtis Jones, Trent Alexander-Arnold, Henderson and Jota.
Eventually, the four were led away by a member of Liverpool's coaching staff. Liverpool legend and Sky co-commentator Jamie Carragher gave the first indication of what had happened, tweeting: "Linesman elbow on Robertson!"
According to Sky Sports reporter Geoff Shreeves, Robertson was furious as he headed down the tunnel. It's understood that the Scot said: "He’s just elbowed me in the throat, the linesman has elbowed me in the throat."
While Robertson appeared to be the victim of the incident, Roy Keane blasted the Liverpool star at half-time. He accused the left-back of being a "big baby".
"Do you know what? Does he grab the linesman first? I’m not sure, but Robertson is then complaining. He should be more worried about his defending. Do you know what he is, that Robertson?" Keane told Sky Sports.
"I’ve watched him a number of times, he is a big baby. That’s what that guy is. Just concentrate on the game and get on with your defending. He does grab the linesman first."
Liverpool and Arsenal played out a thrilling draw at Anfield in what became an instant classic. The Gunners quickly went ahead through Gabriel Martinelli, before the winger turned provider to set up Gabriel Jesus for their second.
But an incident involving Granit Xhaka set the game alight, with Mohamed Salah soon pulling a goal back. Roberto Firmino equalised late on, before Arsenal keeper Aaron Ramsdale pulled off a string of stunning saves to secure a point.
