Pictures published by The Scottish Sun show the nationalist politician speaking to several elderly people in a pub without wearing a face mask. Confronted about the incident Ms Sturgeon admitted she was “in the wrong” and claimed to be “kicking herself” over the lapse in rules.
She added: “This was a stupid mistake and I’m really sorry.”
Under laws passed by the SNP it is illegal in Scotland to go maskless in a pub or bar unless you are sitting at a table.
The incident took place last week at the Stable Bar and Restaurant in Mortonhall, Edinburgh.
Speaking to the Sun one of the pub’s patrons said they were shocked to see the SNP leader breaking Scottish government law.
Ms Sturgeon had been attending the funeral of a Scottish civil servant at Mortonhall Crematorium.
According to Schedule 7 of Scotland’s Health Protection (coronavirus) regulations it is a “requirement to wear face coverings in certain indoor places” such as pubs and restaurants.
The only exception is if you are “seated at a table” which the first minister was not.
Breaches of these rules can result in a fine of £60, though this is lowered to £30 if paid within 28 days.
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The SNP leader’s actions caused outrage on social media.
Pro-union campaign The Majority mocked the Scottish Governments ‘FACTS’ slogan tweeting: “The FACTS are #ResignSturgeon.”
Another Twitter user added: “I know it is tough to lose a First Minister at the height of a crisis, but when it’s a choice of that or integrity of vital public health advice, the latter must come first.”
This tweet received more than 300 likes and 120 retweets.
The rule mandating face coverings in pubs and restaurants, except when seated, was announced on September 10.
Four days later Ms Sturgeon said: “It is now mandatory for customers in those settings to wear face coverings when they are not eating or drinking.
“For example, when you go into the premises and go to your table, or when you stand up to move around to go to the bathroom.”
The UK has seen an explosion in coronavirus cases over the past couple of weeks which the Government has linked to a new more infectious Covid-19 strain.
Earlier this week Ms Sturgeon banned travel between Scotland and the rest of the UK to stop the strain spreading.
From Boxing Day all of Scotland will be placed in a full lockdown for three weeks.