Craven told Inverness boss Terry Butcher earlier this season of his intention to quit his officiating role at Christmas time following confrontations with SFA head of referee development Hugh Dallas and his assistant John Fleming.

The 42-year-old anticipates other officials could follow after he opted to bring his resignation forward.

"Morale is low, rock bottom in fact," Craven told the Sunday Mail. "But it is down to the pressure being put on some officials by Dallas.

"I'd had enough of Hugh Dallas and John Fleming. For a while I felt I had been the victim of harassment and bullying from them.

"Hugh has changed some things for the better, but I just wish he'd stop treating the officials like children. A lot of guys are not happy with it and are ready to walk away."

Craven has been at the centre of the furore which followed the October 17 Clydesdale Bank Premier League clash between United and Celtic at Tannadice.

Referee Dougie McDonald was on Friday cleared over his decision to rescind a penalty awarded to Celtic during their 2-1 victory, but accepted his match report was not up to standard.

The SFA's referees committee unanimously decided McDonald was correct to order a drop ball after initially pointing to the spot following United goalkeeper Dusan Pernis' challenge on Gary Hooper.

Celtic wrote to the SFA demanding clarification over the incident but SFA chief executive Stewart Regan on Friday denied the correspondence had prompted his investigation.

Regan, who instigated the inquiry, revealed McDonald had been given a "warning" by the referees committee over his failure to properly articulate Craven's role in his report and in discussions with the referees observer.

Assistant referee Craven, who was consulted by McDonald before the referee reversed the decision, quit after initially being cast as the instigator of the U-turn.

In the days immediately after the incident, which Celtic manager Neil Lennon branded "unacceptable", Dallas explained that Craven had alerted McDonald to his error.

However, the SFA inquiry discovered that McDonald immediately realised he may have made a mistake and approached Craven unprompted. McDonald then changed his decision after Craven confirmed that Pernis had touched the ball first.

Craven claims McDonald had asked him after the match to lie by saying he called the referee over to query the penalty decision.

Craven now suggests that Dallas was slow in accepting his version of events.

Craven added: "When Hugh phoned me to talk over the penalty, he said: 'So what happened after you called out for Dougie to come over?'

"I told him that was not the case. My reading of the situation was Hugh wanted to protect Dougie and leave me to take the flack.

"I was really upset after that conversation with Hugh."

Craven received a letter stating his resignation had been formally accepted on Friday morning, but plans to continue to referee at amateur level.