Mr Johnson’s former senior adviser has denied being responsible for the leak of private texts in which the Prime Minister promised to “settle” a tax problem for entrepreneur Sir James Dyson.
He said he had also warned Mr Johnson against plans to secretly charge donors for renovating his Downing Street apartment, saying they were “unethical, foolish (and) may -be illegal “.
“It is sad to see the Prime Minister and his office fall so far from the standards of competence and integrity that the country deserves,” he said.
Mr Johnson has since denied seeking to block the investigation.
Asked if LBC radio had tried to stop the investigation, Mr Johnson replied “No, of course not”.
When asked if he thought Mr. Cummings had disclosed details of his contact with entrepreneur Sir James Dyson, he replied: “I don’t think people care about this.
“What interests them is what we were doing to protect the health of the British public and that is what matters to me.”
His attack follows briefings in a number of newspapers, which said Mr Johnson believed Mr Cummings was the source of the leaks regarding the lockdown and its texts to Sir James as well as stories about the renovation of the apartment.
The government also officially declared for the first time that the Prime Minister paid the cost of the renovation of the Downing Street apartment out of his own pocket.
In his blog post, Mr Cummings accused new Head of Communications No.10 Jack Doyle of making false accusations against him “at the request of the Prime Minister”.
He said that although Mr Johnson passed some of his WhatAapp exchanges with Sir James on to him, they did not include those featured in the BBC leak.
He said he was happy to meet with Cabinet Secretary Simon Case to discuss what had happened and to have his phone searched.
He also denied being the so-called “talkative rat” responsible for the leak last October that allegedly “pushed” the government to announce a second lockdown.
He said Mr Case told him and Mr Johnson that “all the evidence” pointed to Henry Newman, a special advisor and close friend of Ms Symonds, and “other people in this office”.
The prime minister had said it would cause him “very serious problems” with his fiancee if Mr Newman were to be fired and asked if the investigation into the leaks could be halted.
Mr Cummings said he told him it was “crazy” and “totally unethical” and that he could not overturn an investigation into a leak that had affected millions “just because that it might involve his girlfriend’s friends “.
Mr. Newman has been contacted by the Standard for comment.
Sky News reports that the allegations against Mr. Newman are “entirely false”.
Sam Coates tweeted: “At Cummings’ suggestion, an investigation into the leaks revealed Assistant Henry Newman was behind the fall lockdown leak, a senior government source said:” The allegations against Henry Newman are entirely false. He would not work in Downing Street if he was suspected of leaking information.
Mr Cummings said there is now an urgent parliamentary inquiry into the government’s conduct during the Covid crisis, with key players required to testify under oath.
Speaking on a partial-election campaign visit to Hartlepool ahead of the release of Mr Cummings’ explosive allegations, Mr Johnson declined to question why his former adviser was suspected in No. 10 of having fled against him.
He again insisted he was right to speak to Sir James who had offered to provide ventilators for the NHS, fearing he would run out of power due to the pandemic.
“I think people are not so much interested in who is disclosing what to whom as the substance of the problem at hand,” he told broadcasters.
“The problem is really the fan issue as you will recall James Dyson proposing to do.”
Former Foreign Secretary Lord Hague said he was unsure whether there was any truth to the claims, but said Downing Street would have to find “right answers”.
“If all of these things were true, they would hurt everyone, including a prime minister,” he told Times Radio.
“But No 10 will undoubtedly have to account for all of these events and I’m sure there will be another side to the argument.”
Labor deputy chief Angela Rayner said the government “swings between cover-ups and scams”.
‘Work focuses on jobs, crime and the NHS as Tories fight like rats in a sack and sink deeper and deeper into the quagmire of dirt,’ she said .
“It shows a breathtaking contempt for the country.”