Celtic striker Leigh Griffiths has been reminded of his responsibilities after hosting a birthday party for his girlfriend.
Pictures emerged on social media of the gathering, which showed friends in breach of the Scottish Government's coronavirus guidelines.
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Phase Three measures allow indoor gatherings with a maximum of eight people from three different households - but social distancing rules still apply.
Hoops boss Neil Lennon told reporters on Friday that the whole squad have been reminded of their responsibilities after two Aberdeen players tested positive for coronavirus. A group of eight Dons players broke the rules by visiting a city centre venue together.
That forced the postponement of Saturday's match with St Johnstone, which has now been rearranged for August 20.
"Celtic takes its response to Covid-19 very seriously," said a club spokesperson. "Clearly, the club cannot comment on enquiries of this nature.
"Safety will always be our priority. To date, we are pleased to be able to report no positive tests."