Matt Hancock has described the release of tens of thousands of his WhatsApp messages as a "massive betrayal".
The under-fire former Health Secretary apologised for the impact of the leak on his political colleagues, aides and friends - and said there was no public interest for the huge data breach.
More than 100,000 WhatsApps were leaked to the Telegraph by political journalist Isabel Oakeshott, who helped the ex-Health Secretary write his pandemic memoir.
The incendiary cache of messages lifts the lid on pandemic decision-making at the top of Government, from care home policy to school closures.
It also dealt a major blow to Mr Hancock's efforts to rehabilitate himself after he was forced out as Health Secretary for breaching his own Covid rules by snogging his aide in a Whitehall office.
In a statement, Mr Hancock said: "I am hugely disappointed and sad at the massive betrayal and breach of trust by Isabel Oakshott(sic).
"I am also sorry for the impact on the very many people – political colleagues, civil servants and friends - who worked hard with me to get through the pandemic and save lives.
"There is absolutely no public interest case for this huge breach."
Mr Hancock said all the materials had been handed over to the Covid inquiry, which was the "right and only place" for the Government's handling of the pandemic to be scrutinised.
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"As we have seen, releasing them in this way gives a partial, biased account to suit an anti-lockdown agenda," he said.
"Isabel and I had worked closely together for more than a year on my book, based on legal confidentiality and a process approved by the Cabinet Office. Isabel repeatedly reiterated the importance of trust throughout, and then broke that trust."
He denied Ms Oakeshott's claim that he sent her a "menacing" late night WhatsApp message following the publication of the first tranche of stories.
He said: "When I heard confused rumours of a publication late on Tuesday night, I called and messaged Isabel to ask her if she had 'any clues' about it, and got no response.
"When I then saw what she'd done, I messaged to say it was 'a big mistake'. Nothing more."
Mr Hancock said he wouldn't comment further until the inquiry.
Questions have been raised over why the former Cabinet Minister entrusted his WhatsApp messages to Ms Oakeshott, a vocally anti-lockdown journalist who has been caught up in several controversies over stories.
Ms Oakeshott branded his defence "ridiculous", telling TalkTV: "For someone who's as intelligent as Matt Hancock to issue a statement saying there is no public interest in these revelations is patently absurd. And he knows that very well."
She stood by her claim that he'd sent a menacing message to her following the reports.
She told BBC Radio 4: "Do you know what I'm not going to do, because it wouldn't be pretty, is get involved in a slanging match with Matt Hancock.
"He can threaten me all he likes. There are plenty of things I can say about his behaviour, by the way, that I'm not going to do - at least not at this stage - because this is not about Matt Hancock. It is so much bigger than that."
Pressed on the claim that he sent a threatening or menacing message, she said: "I'm saying that he sent me a message at 1.20am in the morning. It wasn't a pleasant message."
