Dominic Cummings, Prime Minister Boris Johnson’s former top adviser, accused the government on Wednesday of failing Britain in its response to the coronavirus pandemic, apologising to the families of the tens of thousands “who died unnecessarily”.

After leaving Johnson’s team late last year, Cummings has become one of his former boss’s most vocal critics over how the prime minister led his team in the early days of the Covid-19 pandemic last year, describing it as “catastrophic”.

Cummings, who was part of Johnson’s senior team during that period, accused the government of moving too slowly to try to tackle the spread of Covid-19, the Prime Minister of changing his mind“10 times a day” and health officials of making ill-judged conclusions about the nature of the virus.

Johnson, in parliament, rejected the allegations saying: “I don’t think anybody could credibly accuse this government of being complacent about the threat that this virus posed, at any point. We have worked flat out to minimise loss of life.”

His spokesman said the government would not be engaging with every accusation made by Cummings.

Cummings accused Johnson’s government of failing the public by reacting too slowly to the spread of the novel coronavirus, leading to unnecessary deaths.

“The truth is that senior ministers, senior officials, senior advisers like me, fell disastrously short of the standards that the public has a right to expect of its government in a crisis like this.”

“And I’d like to say to all the families of those who died, unnecessarily, how sorry I am for the mistakes that were made and for my own mistakes.”

“Number 10 was not operating on a war footing in February on (Covid) in any way shape or form. Lots of key people were literally skiing in the middle of February.

“It wasn’t until the last week of February that there was really any sort of sense of urgency I would say ... in terms of Number 10 and cabinet.”

On March 12, Cummings said the situation in Downing Street was “almost surreal”, describing Johnson’s fiancee’s anger about a newspaper article about their dog as competing for attention with planning to tackle the pandemic.

He said Johnson was told on March 14, 2020, he needed to implement a lockdown, but the government did not have a plan. “On the 14th we said to the Prime Minister: ‘You are going to have to lockdown’ — but there is no lockdown plan, it doesn’t exist,” Cummings said.

He quoted Helen MacNamara, former deputy cabinet secretary, as saying: “We are absolutely f***** ... I think we’re going to kill thousands of people”.

Johnson announced a lockdown on March 23.

Asked by opposition Labour leader Keir Starmer whether he accepted Cummings’s central allegations, Johnson said: “No.”