Police are investigating claims that Rangers players used “sectarian language” during their title celebrations.
A probe was launched after TikTok footage emerged of players and others singing inside a function suite.
Rangers declared themselves confident that no criminality had taken place.
“We are aware of a video circulating on social media apparently showing Rangers players using sectarian language while celebrating on Saturday,” a Police Scotland statement read.
“We are assessing its contents and will liaise with the Crown Office and Procurator Fiscal Service as part of our enquiries.”
Scottish Justice Secretary Humza Yousaf said that Rangers should sack any guilty players.
Yousaf wrote on Twitter: “I have also been made aware of this clip, if (and I stress if) this clip is genuine then any player or staff member found to be guilty of anti-Catholic hatred should be shown the door by the Club. It is right Police Scot investigate & determine the facts around it.”
Rangers responded with a club statement which read: “It is evident that this video was shared with an adjoining narrative which attempts to discredit our players and the reputation of Rangers Football Club. This highlights the dangers of ‘trial by social media’.
“It is deeply concerning that this video has been taken as genuine and has been shared widely including by some political representatives who should be mindful of their influence and legal processes.
“Our squad is richly diverse. Sectarianism is unacceptable and has no place in our club which is underlined by our Everyone Anyone campaign.
“We are confident that no criminality took place, we have sought legal advice and look forward to cooperating with Police Scotland.”
The club and Scottish football authorities had earlier criticised the behaviour of fans in Glasgow on Saturday. Police in riot gear broke up celebrations in George Square hours after the team lifted the Scottish Premiership trophy following their final game against Aberdeen.
Five police officers were injured and 28 arrests made – with the force promising many more will follow – after ugly scenes accompanied a mass gathering which flouted Covid-19 rules a day after Glasgow was given notice of further restrictions.
Footage emerged of fans fighting with each other and missiles being launched at police as they dispersed the gathering of an estimated 15,000 people.
Calum Steele, general secretary of the Scottish Police Federation (SPF), tweeted images of injured officers, including broken bones and lost teeth.
Rangers condemned the scenes after describing the support from “millions of our fans across the world” as “incredible”.
A club statement added: “We are grateful to Scottish Government officials, Glasgow City Council and Police Scotland for the constructive engagement in the lead up to the weekend’s game.
“We worked closely with the authorities for two weeks before Saturday’s match to ensure a consistency of message.
“Sadly, a small minority of people behaved inappropriately and in a manner not reflective of our support.
“Some of the scenes were unacceptable and have besmirched the good name of Rangers Football Club. These so-called ‘fans’ should reflect upon the values and ethos of our club, and consider the damage this does to the reputation of the club.
“We will continue to engage with authorities as required.”
Scottish Football Association president Rod Petrie claimed the George Square scenes had “brought embarrassment to the national game”.
“Scenes that require the First Minister, Justice Secretary, Police Scotland and the Scottish Police Federation to issue condemnatory statements, and images that dominated the news agenda throughout the weekend, represent an abomination not a celebration,” Petrie added.
“Those responsible for sectarian singing, for vandalism and for inflicting physical damage may attach themselves to football but cannot be considered football fans.
“Events on Saturday at George Square served only to depict our game in the poorest light and we condemn the behaviour in the strongest terms.
“We empathise with fans who have been deprived of attending matches throughout this pandemic. That, however, does not excuse the behaviour of those who brought chaos to the streets in the name of football this weekend.”
The Scottish Professional Football League described behaviour of fans outside Ibrox and in the city centre as “utterly shameful”.
A spokesperson added: “As the club themselves have said, this behaviour was unacceptable, and especially so given the repeated advance warnings regarding social distancing.
“At a time when everyone in the game is working hard to enable long-suffering fans to get back into stadia, it is simply the last thing that Scottish football needs.
“The police, emergency services and ordinary members of the public did not deserve to be caught up in this melee. We fully support the actions of the courts, the SFA and the club in dealing severely with those who have so badly let the game down.”
Scotland’s deputy first minister, John Swinney, said the scenes were “absolutely reprehensible”.
“There was absolutely no need for them to gather, absolutely no need whatsoever, and the warnings were given very clearly… and then some of them went on to behave in a loutish and thuggish fashion in George Square – devastating property, circulating and expressing vile anti-Catholic bigotry in the centre of the city of Glasgow,” he told BBC Radio Scotland’s Good Morning Scotland.