RONNY DEILA has urged the Celtic fans to be on their best behaviour after Uefa opened disciplinary proceedings against the Parkhead side.

The SPFL Premiership leaders are being investigated after an incident which occurred last week in Zagreb as Celtic lost 4-3 to Dinamo Moscow.

Some Celtic fans let off a flare and are now being investigated for crowd disturbances. The likelihood is that the club will face a financial sanction for the offence, but Inter Milan have previously had their stadium closed by Uefa because of fan trouble, and Deila is wary that further incidents could lead to more serious consequences.

It is the fifth time in three years Celtic have been in the dock with the governing body. The club were fined just over £12,000 in 2011 after supporters made pro-IRA chants during a Europa League home match against Rennes.

They were then handed a further £21,000 punishment after a section of the support unfurled a banner in Udinese criticising the European governing body and also let off flares in the same game.

The letting off of fireworks during a Champions League qualifier against Cliftonville at Celtic Park in July, 2013 led to a fine of just over £4,000, while last year they were hit with a £42,000 sanction for an "illicit" banner on display at a home defeat to AC Milan.

"I think it is very sad if this is the consequences [closed stadium] because 99 per cent are very good supporters, with a very good reputation and that one per cent we have to stop," said Deila.

"Because if now that [closed stadium] could be the end product and that is not good for the club or Scottish football. Always if you continue doing the same mistakes you will get consequences and that is how it is.

"Hopefully now it is nothing big and we can stop this right now."

While he has admitted it is very difficult for the club to police, he has urged supporters to take some responsibility.

"We need to be finished with it and concentrate on football," he said. "It's about values and how we want other nations and teams and people to look at Celtic.

"It's been fantastic for so many years and 99.9% is good now as well. That's one of the biggest things about Celtic - the supporters - and we have to keep up that reputation.

"It is very hard for the club to control. It is the responsibility of supporters and supporters' clubs."