The Norwegian said: “We can’t just wait until a serious injury happens and then take action. It has to be taken now.
“Someone throwing a bottle, that’s as far away from acceptable as possible. It is unforgivable; I think that’s the point that needs to be understood.”
The problem of missile throwing from supporters and assaults on players and officials has steadily increased this season, culminating in shameful incidents during the Scottish Cup quarter-final ties at the weekend.
Coins and an empty Buckfast bottle were launched from among the Hibernian fans at Easter Road as Celtic winger Scott Sinclair went to take a corner. Seats were ripped out in the Rangers end at Pittodrie and Partick Thistle manager Gary Caldwell had coins thrown at him by Hearts supporters during a tie few would have categorised as high risk.
Ajer added: “The bottle incident and coins being thrown, you can’t really accept that. When you play football there are strong feelings. You know how much every single person in the stands cares about their club.”
The bottle thrown at Sinclair could have led to the 29 year old requiring hospital treatment and Ajer believes that his peers have reached a tipping point.
“To be honest, I don’t know what would have happened it it had hit Sinky. It would have caused really, really severe injuries if he had been hit on the head.
“Maybe some actions would have been taken, but, thankfully, it didn’t happen.”
The 20-year-old centre back insists something must be done so that players can feel secure at their place of work.
However, in a weekend where Hibs host Rangers and Aberdeen visit Celtic Park, the fear is that things could become worse before they get better.
“It’s important that we come to a point where you go out on to the pitch and feel safe,” said Ajer.
“Hopefully, that will be taken care of because you don’t want to see that.
“When there is so much tension in every single game fans here, in terms of supporting their team, are fantastic.
“But a few times this season it has really crossed the line, which you cannot accept.
“It’s important to get back to the time before when you walked on to the pitch and didn’t expect something bad to happen – and which has happened way too many times this season.
“As a player, you expect a lot of stick from the stands because you know there is feeling,” he said. “I would never take away the really fantastic atmosphere there can be in Scotland like when you play against teams and the crowd makes fantastic noise.
“I look at the Scottish fans, mostly, as among the best in the world, but you don’t want it to cross the line of getting dangerous.