The Scottish Government is considering a suspension of football after Celtic defender Boli Bolingoli's secret trip to Spain threw the season into disarray.
Bolingoli failed to quarantine for 14 days as required when he returned from Spain and the left-back came off the bench during the 1-1 Scottish Premiership draw with Kilmarnock on Sunday.
Celtic have condemned what they admitted was inexplicable and "stupid" behaviour.
News of the Belgian's mini break emerged three days after First Minister Nicola Sturgeon issued Scottish football with a stark warning after eight Aberdeen players broke protocols with a night out.
The Dons' weekend game against St Johnstone was postponed after two of their players tested positive for Covid-19 and a further six were instructed to self-isolate.
Justice minister Humza Yousaf wrote on Twitter: "Utterly unacceptable from Bolingoli. With a number of incidents, Scot Govt left with little choice but to consider whether pause is now needed in resumption of the game.
"Operational matter for Border Force & Police Scot, I support whatever enforcement action they deem necessary."
The Scottish football authorities are now holding more talks with the government – managers and captains from the 12 Premiership clubs had held video talks with national clinical director Jason Leitch on Monday evening where they were reminded of their responsibilities.
A Scottish Government spokesperson said: "We are currently in discussion with the club and football governing bodies to establish the facts.
"If confirmed as another serious incident within Scottish football, where protocols have been breached at the risk of wider public health, then the Scottish Government will have little choice but to consider whether a pause is now needed in the resumption of the game in Scotland."
A statement from the Scottish champions read: "Celtic Football Club unreservedly condemns and apologises for the behaviour of the player Boli Bolingoli in travelling to Spain without informing the club and in failing to observe quarantine restrictions.
"It is difficult to imagine a more irresponsible action in current circumstances and we find it beyond explanation. The club will take immediate action through our own disciplinary procedures.
"Celtic are in touch with every SPFL club today, and with all relevant authorities, to apologise for the fact that one of our employees has created so much additional difficulty through his actions.
"All of our playing and backroom staff have been tested twice for Covid-19 since this incident and all, including the player in question, have tested negative. While this comes as a relief to all concerned, it in no way diminishes the seriousness or stupidity of the player's actions.
"Since the Covid -19 crisis began, we have had a safe and healthy squad of players, recording not one positive test. As a club, we have worked tirelessly to ensure a sustained, safe environment for all.
"We have led the way in working with the football authorities and Scottish Government to establish the most rigorous, effective protocols and working practices, which ultimately led to the resumption of football. We could have done no more in this area.
"It is a matter of the deepest regret to us that the behaviour of one individual has jeopardised that reputation and reflected discredit on football more generally."
Motherwell manager Stephen Robinson argued it would be wrong to shut down an industry for individual mistakes.
Robinson said: "People will lose jobs, the industry will go to pieces, make no mistake about that. I just don't think in any shape or form Scottish football should be closed down. It's individual errors, if they are true.
"I see from every club and every person I speak to in Scottish football, we are doing more than any other industry, 10 times more, but it doesn't sell papers.
"When one person makes a mistake it goes all over the place and gets exaggerated tenfold. I am not condoning anything that happened but it is being dealt with."
Even if Scottish football survives its latest indiscretion, Aberdeen's home game against Hamilton on Wednesday is not certain to go ahead given the spike of cases in the city.
