It comes as Allegra Stratton has just quit her role as the Prime Minister's spokesman for Cop26 after footage emerged of her joking about a Christmas party at Downing Street.
Video of a mock press briefing showed Ms Stratton quipping "I went home" in response to a hypothetical question, in which she referred to a "fictitious party" that was "not socially distanced".
Offering her "profound apologies" for her remarks, Ms Stratton said in a statement: "My remarks seemed to make light of rules, rules that people were doing everything to obey. That was never my intention.
"That was never my intention. I will regret those remarks for the rest of my days and offer my profound apologies to all of you for them.
"I understand the anger and frustration that people feel. To all of you who lost loved ones, endured intolerable loneliness and struggled with your business - I am sorry and this afternoon I have offered my resignation to Prime Minister."
Offering her "profound apologies" for her remarks, Ms Stratton said in a statement: "My remarks seemed to make light of rules, rules that people were doing everything to obey. That was never my intention.
"That was never my intention. I will regret those remarks for the rest of my days and offer my profound apologies to all of you for them.
"I understand the anger and frustration that people feel. To all of you who lost loved ones, endured intolerable loneliness and struggled with your business - I am sorry and this afternoon I have offered my resignation to Prime Minister."