Celtic chief executive Peter Lawwell has admitted that the club's trip to Dubai last week was "clearly a mistake" after defender Christopher Jullien tested positive for Covid-19.
Following Jullien's positive test, manager Neil Lennon and 13 senior players were forced into self-isolation having come into contact with Jullien during the trip.
Initially, the club defended their decision to travel to the Middle East for training, but Lawwell has now said that travelling during a coronavirus surge was ill-advised.
"On reflection, looking back and looking with hindsight and looking at the outcome of the trip, clearly it was a mistake and for that I profoundly apologise to our supporters," Lawwell told Celtic's official website.
"This horrific pandemic has affected the whole of society. It's affected people here in Scotland, it's affected our supporters, it's affected our football and it's affected our club - probably our club more than any."
Celtic's trip generated further controversy when photos emerged of players and staff not wearing masks or social distancing at various points during the trip.
Even Scotland First Minister Nicola Sturgeon weighed in on the journey to Dubai, saying she was "disappointed" and "frustrated" by Celtic's actions in the United Arab Emirates.
“This whole episode should underline how serious the situation we are in right now is and why everyone – including football – should be erring on the side of caution," Sturgeon said earlier this week. “I would hope Celtic themselves will reflect seriously on all of this.”
Lawwell admitted that the recent surge in Covid-19 cases across the UK meant his team's trip should have been reconsidered.
"Clearly the landscape has changed significantly - particularly in the run-up to us going to Dubai - in terms of the infection rate," he added. "The protocols were robust, they're proven, and that's what we put in place for the Dubai trip.
"Overall, the decision to go was for the right reasons - it was performance - and of course the outcome of that has been really disappointing. I do understand how people are questioning the decision to go."
Celtic currently sit 21 points behind Scottish Premiership leaders Rangers but do have three games in hand.