The Scottish Sun has published a photograph of the First Minister standing talking to three pensioners at a distance, but with her face uncovered in an Edinburgh restaurant.
The picture is reported to have been taken at the Stable Bar and Restaurant following the funeral of a Scottish Government civil servant at Mortonhall Crematorium.
The paper quotes the First Minister admitting she had made a “stupid mistake” and was “kicking herself”.
Under Scottish Government coronavirus rules, customers in hospitality venues must wear a face covering except when seated and must wear one when moving around.
The story, which is written by the paper’s political editor Chris Musson, quotes Ms Sturgeon saying: “Last Friday, while attending a funeral wake, I had my mask off briefly. This was a stupid mistake and I’m really sorry.
“I talk every day about the importance of masks, so I’m not going to offer any excuses. I was in the wrong, I’m kicking myself and I’m sorry.”
A Scottish Conservative spokesman said on Tuesday night the “First Minister should know better” and claimed “it’s a blunder that an ordinary member of the public wouldn’t get away with”.
In the regulations introduced on September 14 in Scotland, face coverings for customers and staff are mandatory when entering, exiting and moving around hospitality venues.
The rules state: “There is an exemption for when customers are seated for the service of food and drink and for back of house roles such as kitchen staff or staff who are behind protective screens separating them from customers.”
Those who breach the face covering rules can face a £60 fine.
Scotland’s Justice Secretary Humza Yousaf tweeted: “FM has approached pandemic by being upfront from v beginning.
“She has apologised for accidental lapse (which I suspect most of us have had one over last 9 months).
“I’ve known her for 15yrs & she is her harshest critic. I am sure most ppl will understand, accept apology & move on.”