Referee Darren Drysdale has apologised after squaring up to and pressing heads against Ipswich Town's Alan Judge in their 0-0 draw with Northampton.
Drysdale and Judge exchanged words in the 90th minute after the midfielder's appeal for a penalty had been turned down before the 49-year-old Lincolnshire official leant into Judge.
Ipswich pair Flynn Downes and Jack Lankester and Northampton defender Lloyd Jones stepped in and calmed the situation before Drysdale booked Judge.
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Drysdale has apologised to Judge and Ipswich in a statement via the PGMOL, saying: "I fully understand that it is important for us as referees to maintain our composure throughout the game and always engage with players in a professional manner. I'm sorry that I did not do that last night and I can only apologise to Alan and Ipswich Town."
An Ipswich spokesman told Sky Sports News that the club have not made any official complaint, but added: "We will leave it to the authorities to decide if there is to be any action taken."
The Football Association confirmed on Wednesday morning it is aware of the incident and is investigating it in line with their usual disciplinary process.
Sky Sports News has contacted the FA and EFL for comment.
Ipswich Town are 11th in Sky Bet League One as a result of the draw, with Northampton moving up a place to 21st but remaining in the relegation zone.
Drysdale, who was appointed to the National List of referees covering EFL games in 2004, has also been a FIFA and UEFA assistant referee and was an assistant referee at the 2000 FA Cup final.
Lambert: FA has to take the right action now
Ipswich manager Paul Lambert said he hopes the Football Association "do the right thing" in its handling of the incident and that he has spoken to Mike Jones (head of EFL referees) regarding it.
"I think the apology is very soft - it's easy to say sorry after the event," Lambert told Sky Sports News. "What happened was incredible, I've never seen that, for a referee to go head-to-head with a player.
"He had to get pulled away by the Northampton players and at that time he's out of control. What would have happened to Alan Judge if he'd done that to the referee? He'd have been looking at a six-month ban, a one-year ban and a massive fine.
"I think the FA have got to have a look at it and I think they'll say they can't defend him. They've got to look at the whole incident really strongly because you can't let things like that happen. I'm hoping the FA will do the right thing.
"The players couldn't believe it. I think they were taken aback by it. They must have seen something close at hand which sparked that and for me that's the key thing. I asked the referee afterwards and asked if he put his head on my player and he told me to get away."
'Keeping calm is everything for a referee'
Former Premier League referee Dermot Gallagher said Darren Drysdale made the crucial mistake of losing his calmness and composure - something all referees must always have.
"It's great that he's apologised, that's first class and it acknowledges that he lost his composure for a few seconds on the pitch," he said.
"It will take its course now. I don't know what was said - it's unusual for a referee to react like that and you have to commend the players for what they did, they defused it very quickly.
"It's interesting that the few times referees get in trouble, the players always pull together to look after them if they get injured or whatever. The players were absolutely excellent in this situation.
"No matter how heated it gets, you still have to maintain this little bit of distance and stay calm, that's the be-all and end-all for referees because if you're composed that's when you make good decisions.
"It's tough at times, it's the nature of the beast. You know it's not going to be a walk in the park. The tough times come and you have to deal with them."