Dominic Cummings, the PM’s former chief adviser, has denied leaking text messages sent between the PM and businessman Sir James Dyson.
Several newspapers have speculated that Mr Cummings passed on the messages, first reported this week by the BBC.
But in his own blog, Cummings writes that he was “not directly or indirectly the source” of the leak – and questions the “competence” of the prime minister.
Asked whether he had blamed his former adviser for it, Mr Johnson said: “I don’t think people give a monkey’s, to be frank, about who is briefing what to who.”
The BBC – whose political editor Laura Kuenssberg first reported on the text messages on Tuesday – said it did not discuss the sources of stories.
For many people, they will be see through this entire fiasco as little more than a diversion.
The real questions apart from how public and accessible the contents of the British prime misters’ personal phone are and to the extent, it’s a guessing game to who leaked what from it are questions about the ministerial code, corruption, and now a clear case of national security and the monitoring of the prime ministers mobile phone.
David Cameron must be laughing in his shed while the attention is taken off him
In the 1000-word blog post, Mr Cummings also wrote that attempts to get a Conservative donor to secretly pay for lavish refurbishments of the Prime Minister’s Downing Street flat was “unethical, foolish, possibly illegal and almost certainly broke the rules”.
The blogpost was written in response to stories in three national newspapers that Mr Cummings was behind this week’s leak of text messages between the Prime Minister and businessman Sir James Dyson.
The leak revealed Mr Johnson had promised Sir James he would “fix” a tax issue for Dyson staff working to develop ventilators early on in the pandemic.
Cummings writes on his blog: “I was not directly or indirectly a/the source for the BBC/Kuenssberg story on the PM/Dyson texts.”
He adds: “I am happy to meet with the cabinet secretary and for him to search my phone for Dyson messages.”
Dominic Cummings continues: “I am happy for No 10 to publish every email I received and sent July 2019-November 2020 (with no exceptions other than, obviously, some national security/intelligence issues).”
He also calls for an “urgent parliamentary inquiry into the government’s conduct over the Covid crisis”, adding that he thinks Mr Johnson has fallen “far below” the standards of “competence” the “country deserves”.
Cummings promises to answer questions about “any” issues when he appears before a parliamentary committee on 26 May.
Earlier, Downing Street declined to comment on “speculation” that Mr Cummings – who quit his government job last November after a row over his role as the PM’s chief adviser – had leaked the texts.
On a visit to Derbyshire, Mr Johnson said anyone who thought there was something “dodgy or rum” in his dealings with Sir James Dyson was “out of their mind”.
But Labour leader Sir Keir Starmer said the it was “increasingly obvious” the prime minister was involved in “sleaze”.