In a new statement on Tuesday evening, the former prime minister hit out at the panel's "absurdly unfair rules" which he claimed prevented him from criticising its findings.

The group of cross-party MPs is poised to conclude that Mr Johnson deliberately misled parliament with his assurances that COVID rules were followed at all times in Downing Street during the pandemic.

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Mr Johnson said: "The privileges committee should publish their report and let the world judge their nonsense.

"They have no excuse for delay.

"Their absurdly unfair rules do not even allow any criticism of their findings.

"I have made my views clear to the committee in writing - and will do so more widely when they finally publish."

Earlier, the committee said that it is dealing with "further representations" made by Mr Johnson's legal team on Monday night as the group met to conclude the inquiry.

No information was given about the submissions, but his last-minute intervention is likely to delay the publication of their findings - which were initially expected to be published on Wednesday.

A committee spokesman said on Tuesday: "A letter enclosing further representations from Mr Johnson was received by the committee at 11.57pm last night.

"The committee is dealing with these and will report promptly."

Mr Johnson previously attacked the seven-person committee, which is chaired by veteran Labour MP Harriet Harman but has a Conservative majority, as a "kangaroo court" when he announced his Commons exit on Friday after receiving a draft of its findings.

It has been suggested that the panel had been discussing a 20-day suspension as punishment for lying, triggering a recall petition and potential by-election.

Mr Johnson cannot be suspended now he has resigned, but he could be refused a parliamentary pass offered to former MPs, a sanction imposed on ex-Commons speaker John Bercow after a bullying report.

The findings are expected to be damaging but despite this, Mr Johnson has insisted "I'll be back" - a reference to Arnold Schwarzenegger's Terminator.

In the Daily Express, the former prime minister said: "We must fully deliver on Brexit and on the 2019 manifesto. We must smash Labour at the next election.

"Nothing less than absolute victory and total Brexit will do - and as the great Arnold Schwarzenegger said, I'll be back."

The message echoed Mr Johnson's sign-off during his final appearance at Prime Minister's Questions last year, when he told MPs: "Hasta la vista, baby" - the catchphrase of Schwarzenegger's cyborg character in the 1991 movie Terminator 2: Judgment Day.

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That reference similarly left the door open for a possible comeback, but the former Uxbridge and South Ruislip MP remained on the backbenches until quitting as a member of parliament on Friday.

Following his shock resignation, Mr Johnson launched into a public spat with Rishi Sunak over his resignation honours list.

Mr Johnson's camp accused him of having "secretly blocked" the peerages of former culture secretary Nadine Dorries and other allies in his resignation list.

The prime minister denied this and claimed his predecessor asked him to "do something I wasn't prepared to do", which was "to either overrule the Holac [House of Lords Appointments] committee or make promises to people".

As Ms Dorries weighed in with her version of events, claiming "sinister forces" were behind her peerages snub, Sir Keir Starmer warned that Tory infighting between the two erstwhile allies is damaging the UK's reputation internationally and putting off investors.

The Labour leader told business chiefs at London Tech Week: "There's a deeper price because there's a reputation hit to the UK.

"I think there's an economic hit as well, many investors said to me, we're not investing in the UK right now because we don't see the conditions of certainty and stability we need in order to invest."