Rangers and Celtic must brace themselves for the worst-case scenario after fans poured onto the ground at full-time.

Keith Hackett, former PGMOL chief and ex-FIFA referee, told Football Insider exclusively that authorities might take severe action following “sinister” incidents at Ibrox on Sunday, March 8.

Danny Rohl and Martin O’Neill’s sides were unable to break the deadlock after extra time, with the Hoops eventually clinching their place in the Scottish Cup semi-finals following a brief penalty shootout.

Rangers’ focus will shift to the Scottish Premiership, but there is certain to be more fallout from the events at Ibrox, and Hackett has proposed some of the harshest punishments available.

‘Sinister’ fans deserve to be punished following Rangers against Celtic.

In an exclusive interview with Football Insider, the former referee stated, “What was particularly upsetting was that fans recognized that stepping onto the pitch is an offence, so they had items over their faces and heads to ensure they were not seen.

“That has a nefarious undertone, in my opinion. I’m sure the authorities will not be pleased. At the end of the day, one has to consider whether games must be played without spectators.

“This is a challenging situation for the authorities. In Europe, fans are banned or stands are closed, yet this affects season ticket holders who have not caused any difficulties.

“There must be an answer. Will we reach a situation where games are played behind closed doors? Fines, bans, and closure of the ground. Or do we reach a point when points are deducted and teams are eliminated from competitions? That is the dilemma.”

Rohl is under pressure at Ibrox, although Football Insider knows that he is not in immediate danger of being fired.

Keith Hackett offers special notice to Don Robertson.

Before discussing the controversy, Hackett stated, “It was a fantastic match, and the referee was excellent. I believe Don Robertson played an excellent game in terms of striking the correct balance.

“Don Robertson’s foundations stem from our appeal for former players to become referees. His judgment and participation were excellent. “It was the performance of the season.”

Robertson handled the heat of the game brilliantly, issuing cautions when necessary and allowing the game to proceed as many desired. But as soon as the final whistle blew, everything turned bad.