Seven members of staff at St Mirren Football Club have tested positive for coronavirus.
No players have so far tested positive and the club said it is taking all possible precautions to ensure there is no further spread.
The Scottish football authorities announced that clubs will have to revert to twice-weekly testing after the requirements were relaxed earlier this month.
St Mirren's planned friendly match at home to St Johnstone, scheduled to take place on July 25, has been cancelled.
In a statement, St Mirren said: "We can confirm our testing regimen has identified several members of our coaching staff have tested positive for Covid-19.
"Thus far no members of the playing staff have tested positive and we are taking all possible precautions to ensure there is no further spread."
The Scottish Football Association (SFA) said the Joint Response Group (JRG) was notified on Thursday that St Mirren Football Club returned seven positive tests for Covid-19.
The SFA said: "We immediately contacted the Scottish Government and the office of the Clinical Director for Scotland to relay this information.
"As a consequence, St Mirren's planned friendly match at home to St Johnstone, scheduled to take place on Saturday 25 July, has been cancelled.
"In light of this and other recent events, the JRG hereby notifies Scottish Premiership clubs that with immediate effect they must revert to twice-weekly testing protocols until further notice."
St Mirren are due to kick off their season at home to Livingston on August 1.
Hamilton, who they faced in a friendly last Saturday, said they are confident their safety protocols will prevent any potential transmission.
A Hamilton Academical spokesman said: "Following the departure of the St Mirren squad on Saturday, the area used was cleaned and disinfected.
"The location occupied by St Mirren was a segregated area at the far end of our stadium and is separate from the areas used by Hamilton Accies' players and staff on a match day.
"Subsequently on Monday, all players and backroom staff were tested with all results returned negative.
"Hamilton Academical will continue to follow advice from the SFA/SPFL joint response group."
