Graeme Stewart was a close contact of fellow assistant referee David Roome, who returned a positive test on Wednesday, having returned from officiating in the match between Panathinaikos and Olympiacos in Athens last Sunday.

The third member of the travelling party, referee Bobby Madden, was stood down shortly before he was due to take charge of Sunday evening's match between Ross County and Celtic.

Hibernian v Celtic – Scottish Premiership – Easter Road — Bobby Madden was stood down from refereeing Ross County v Celtic on Sunday evening (Andrew Milligan/PA)

In a statement on Sunday evening, the Scottish FA acknowledged that despite having submitted two negative tests each since returning, both Madden and Stewart should have been considered close contacts under Scottish government regulations, thus ruling Stewart out of officiating on Saturday.

The statement read: "We are aware that Graeme Stewart was assistant referee at yesterday's Premiership match between Hibernian and Hamilton Academical.

"We have informed both clubs as part of a review of process initiated today and Dr MacLean has informed the Elite Sports Clinical Advisory Group.

"No players or members of team staff involved in yesterday's match have been identified as close contacts of Graeme.

"As a result, all three match officials must now undertake 10 days of self-isolation dated from Monday 15 February, as the date of last contact for Bobby and Graeme, and from Tuesday 16, the date of the positive test for David."

Scotland v Israel – UEFA Euro 2020 – Play-Offs – Semi Final – Hampden Park — SFA chief executive Ian Maxwell has apologised for the 'breakdown in internal process' (Andrew Milligan/PA)

Scottish FA chief executive Ian Maxwell said the circumstances of the case were "complex", but confirmed he had apologised to the clubs concerned.

Maxwell said: "I have tonight apologised to Hibernian and Hamilton Academical for the unnecessary risk of having an assistant referee at a match when he should have been self-isolating, however much it is mitigated by two negative tests in the build-up to the match.

"As part of an internal review, I have asked the respective departments to ensure we maintain the highest standards of compliance relevant to Scottish Government protocols."

Neither Hibernian nor Hamilton were immediately available for comment.