Celtic defender Kristoffer Ajer has warned the missile throwers shaming Scottish football they risk "destroying" the game's reputation.

There have been fresh demands for the introduction of strict liability after Hoops star Scott Sinclair narrowly avoided serious injury when a glass bottle was hurled towards the winger from the Easter Road stands during Saturday's William Hill Scottish Cup win over Hibernian.

It was among the latest in a string of incidents that have dragged the Scottish game into the gutter this season, with Partick Thistle boss Gary Caldwell also targeted with a coin during the Firhill clash with Hearts on Monday.

However, Norwegian ace Ajer claims a "line has been crossed" with the shocking Sinclair episode in Leith.

Now the former IK Start centre-back has called for action to be taken before both a player and the esteem the Scottish game is held in suffer significant harm.

"What happened on Saturday was really, really disappointing," he said. "Hopefully some action will be taken before a serious injury happens because you can't sit and wait for the first really bad injury to happen before something is done.

"If that bottle hits Sinclair it could have caused a severe injury. He was lucky not to be hit.

"Too many times this season a line has been crossed.

"For me, I've always thought that Scottish fans are the best in the world in terms of creating an incredible atmosphere and fantastic noise. Without a doubt, this is one of the best countries in the world to play in for atmosphere.

"But a few fans are destroying the whole picture you get from the stands because of these coins and even a bottle being thrown at the players.

"That is completely unacceptable and a real shame. To see these situations being the headlines is really quite sad."

Hibs have vowed to invest in improved CCTV coverage after admitting their current system failed to pick up the offender responsible for taking aim at Sinclair.

But Ajer stressed: "These incidents need to be taken of. They're not great for Scottish football and I hope some action is taken.

"I think it's important to explain that the majority of Scottish fans and people are fantastic. Hopefully the few bad incidents can be taken away."

Celtic were able to sidestep the threat posed by Paul Heckingbottom's side as a 2-0 win booked a semi-final against either Aberdeen or Rangers.

And Ajer says that is testament to the way new boss Neil Lennon and his number two John Kennedy have dealt with the upheaval since Brendan Rodgers' exit.

"The win at Easter Road was a big achievement for us," he said. "The manager has had a really good talk with the squad and told us about the future going forward. He's been talking to individuals and the squad as a whole.

"The togetherness in the dressing room has been really good and our captain Scott Brown has been a real leader. The whole feeling around the club is that everyone is looking forward now.

"Kendo has taken a lot of training too this week. I've been working really closely with him for the three years I've been here.

"I changed position from a midfielder to a centre-half when I came here and we have spent a lot of time on the pitch working on all the positional and technical stuff that I had to develop.

"It might only be 20 minutes but I'm thankful for all he's done for me. It's no surprise he's stepped up to become the gaffer's number two. He's a top man."