SNP Westminster leader Ian Blackford said Boris Johnson had “no option” but to sack Dominic Cummings, and his failure to do “is a gross failure of leadership”.
Responding to the extraordinary press conference in the Downing Street garden, Mr Blackford said: “What should have been a resignation statement turned out to be a botched PR exercise that changes nothing. It is now beyond doubt Dominic Cummings broke multiple lockdown rules.
“There was no apology and no contrition from Mr Cummings for his behaviour – and now, following this unrepentant press conference, there are no excuses left for him.
“He has done nothing but double down on the double standards he has displayed and which millions of people across the UK are furious about.”
Earlier, Cummings defended his decision to travel 260 miles with his family during the coronavirus lockdown.
Cummings, a key aide of Prime Minister Boris Johnson, said his decision to drive to his parents’ home in County Durham was based on concerns about his family’s safety, as well as fears over a lack of childcare if he became incapacitated with the virus.
But his explanation failed to satisfy many across the political spectrum.
Acting Liberal Democrats leader Sir Ed Davey tweeted: “Cummings’ statement confirms he broke the guidelines. When millions kept to those rules. The PM must now terminate his contract – if he wants to regain any credibility in leading the country on dealing with the coronavirus crisis.”
Meanwhile, a spokesman for the Labour Party said: “The British people were looking for at least an apology from Dominic Cummings for breaking the lockdown. They got none.
“Millions of people have made extraordinary sacrifices during the lockdown. Families have been forced apart, sometimes in the most tragic of circumstances. They stayed at home to protect the NHS and save lives.
“And yet, the message from this Government is clear: it’s one rule for Boris Johnson’s closest adviser, another for everybody else.”