Dominic Cummings has blasted Boris Johnson and his office for falling “so far below the standards of competence and integrity the country deserves”.
In a lengthy statement, the PM’s ex-aide denied being the source of leaked messages from Mr Johnson’s phone and tore into his former boss.
And in an explosive claim, he suggested Mr Johnson was prepared to potentially break electoral law by asking donors to pay for the refurbishment of his Downing Street flat.
Mr Cummings was blamed by No10 sources after texts between the Prime Minister and businessman James Dyson ended up in the hands of the BBC.
In a post on his blog, Mr Cummings said: “I do have some WhatsApp messages between the PM/Dyson forwarded to me by the PM.
“I have not found the ones that were leaked to Laura Kuenssberg on my phone nor am I aware of being sent them last year.
“I was not directly or indirectly a/the source for the BBC/Kuenssberg story on the PM/Dyson texts.”
He said he is “happy to meet with the Cabinet Secretary” and to have his phone searched.
This breaking story is being updated.
