Celtic defender Kristoffer Ajer has called on the police, the game’s ruling bodies and the clubs to ensure that football grounds become safe spaces for players and spectators again.

The Norwegian revealed that the recent spate of violent incidents inside stadia – which is fast becoming a trend - has led to footballers feeling less secure in their working environment.

In the last five months former Hibernian manager Neil Lennon sustained a head wound after being struck by a coin thrown from the Hearts support during a 0-0 draw at Tynecastle and Hearts goalkeeper Zdenek Zlamal was punched by a Hibs fan.

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During the same game assistant referees David McGeachie and Frank Connor were struck by missiles, while colleague Calum Spence was cut by a coin thrown by a Rangers fan during his side’s 1-0 defeat at Livingston.

Rangers striker Alfredo Morelos was on the receiving end after scoring against St Mirren in Paisley, Kilmarnock captain Kris Boyd was pelted by a coin launched by a Celtic supporter and Red Bull Salzburg defender Andre Ramalho was hit on the head during a Europa League tie at Parkhead.

Last weekend coins and an empty Buckfast bottle were thrown at Celtic winger Scott Sinclair as he was about to take a corner during his side’s 2-0 Scottish Cup win at Easter Road. Less than 24 hours later Rangers and Aberdeen hooligans ripped out seats and threw them at each other during their 1-1 draw at Pittodrie and Partick Thistle manager Gary Caldwell was targeted by a coin-throwing Hearts fan on Monday night.

The increasing frequency of the incidents has left players feeling in harm’s way and, as Ajer contends, they cannot be expected to give of their best in those circumstances.

“It’s important that we come to a point where you go out onto the pitch and feel safe,” said the 20-year-old.

“The last game you talk about, with 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.

“To be honest, I don’t know what would have happened if 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."

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He added: “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 terns 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 onto the pitch and didn’t expect something bad to happen - and which has happened way too many times this season.”

The bottle launched at Sinclair could have led to the 29-year-old requiring hospital treatment and Ajer believes that his peers have reached a tipping point.

“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.

“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.”

Kristoffer Ajer was speaking as Celtic, in association with the Centre for Access to Football in Europe (CAFE), announced its support for a European-wide week of action which celebrates the wider inclusion of disabled people and the important role they can play in both football and wider society.