Assistant referee Constantine Hatzidakis stood down amid FA investigation into Andy Robertson elbow incident

Assistant referee Constantine Hatzidakis will not be involved in any matches while the FA investigates an incident in which he appeared to elbow Liverpool defender Andy Robertson, PGMOL has announced.

Hatzidakis was involved in an incident with Robertson at half-time during Liverpool's 2-2 draw with Arsenal at Anfield on Sunday.

Robertson appeared to be elbowed in the face by Hatzidakis when he approached the official at the end of the first half, with footage showing the linesman raising his arm in the direction of the Liverpool defender.

Robertson was subsequently booked for dissent by referee Paul Tierney.

Liverpool boss Jurgen Klopp declined to comment after the match and said he did not witness the incident.

"I didn't see it and I now have obviously time to watch it but I didn't just because I cannot give wrong answers," said Klopp.

"I heard the pictures speak for themselves. I cannot say more. I didn't see a bit of it."

The FA and PGMOL, the professional referees' body, immediately launched an investigation into the matter after the draw at Anfield.

PGMOL has now confirmed that Hatzidakis has been stood down from officiating duties while the investigation continues.

"PGMOL will not be appointing Constantine Hatzidakis to fixtures in any of the competition it serves whilst The FA investigates the incident involving the assistant referee and Liverpool defender Andrew Robertson at Anfield," read a PGMOL statement released on Monday.

Hackett: Hatzidakis' career in jeopardy

Former Premier League referee Keith Hackett says Hatzidakis' career as a linesman could be in 'jeopardy' if he is found guilty of striking Robertson.

"You never what is going through the mind of match officials now," Hackett said on BBC Radio 5 Live.

"The atmosphere was electric [at Anfield], there are different temperatures and thoughts within a match official, and it was such an unprecedented view.

"I was trying to find an excuse as to why he did it and I came up with was he in fear? He shouldn't be, because he's in a protected environment with plenty of security.

"But he reacted in a way that he shouldn't have reacted at the end of the day and here we are talking about a match official and not a decision, but an action by a match official - and he's clearly lost his composure.”

Meanwhile, Robertson was criticised by former Manchester United captain Roy Keane, who labelled him a 'big baby' over his behaviour.

Keane said on Sky Sports: "Robertson, do you know what, does he grab the linesman first? I'm not sure, but he's complaining. He should be more worried about his defending.

"Do you know what it is, that Robertson? I've watched him a number of times. He's a big baby. That's what he is. Just get on with the game and concentrate on your defending. He does grab the linesman first."