The publication of the report expected to find Boris Johnson misled Parliament over the Partygate scandal has been delayed until at least Thursday.
The findings of the Privileges Committee were expected to be released earlier this week, but an 11th-hour intervention from the former Prime Minister has been blamed for the hold up.
Mr Johnson quit as MP for Uxbridge and South Ruislip on Friday after receiving a private copy of the report.
His lawyers then sent a letter to the committee just before midnight on Monday night pushing back on its conclusions.
MPs on the cross-party group, which has a Tory majority, had been hoping to bring their year-long inquiry to an end on Wednesday. But the letter from Mr Johnson, as well as a large operation to draft and print the report, has slowed down proceedings.
But Mr Johnson has urged the Privileges Committee to publish and “let the world judge their nonsense”.
In a statement on Tuesday night, he lashed out at the panel’s “absurdly unfair rules”, which he said prevented him from criticising its findings, and vowed to make his “views clear” when they are released.
The committee said Mr Johnson had made last-minute representations ahead of the release of its report, which is expected to find that he deliberately misled the Commons with his assurances that lockdown rules were followed in Downing Street.
The committee said it was “dealing with” submissions received from the ex-premier at 11.57pm on Monday.
The publication of its findings had already been pushed back towards the end of this week, reportedly due to printing problems in Parliament, before Mr Johnson’s 11th-hour representations.
In response, 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.”
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.
A Privileges 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.”
The MPs on the panel have rejected Mr Johnson’s defence that senior officials advised him Covid rules and guidance had been followed in No 10, according to the Times.
A senior aide in fact warned him against claiming to the Commons that social distancing guidelines were observed, the newspaper reported.
Following his shock resignation, Mr Johnson launched into a public spat with one-time ally Rishi Sunak over his resignation honours list.
The Prime Minister suggested his former boss wanted him to ignore the recommendations of the House of Lords Appointments Commission.
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 Conservatives poured activitists into Ms Dorries’ Mid Bedfordshire constituency over the weekend, where they are defending a 24,664 majority.
But as of early Wednesday morning, she had yet to formally resign, sparking speculation that she may stay on to cause more chaos for Rishi Sunak.
A long delay would mean that the Prime Minister may not be able to hold all three by-elections on the same day, which might have limited the political fall-out if the Tories lose two or three of them.
Conservative peer and pollster Lord Robert Hayward told The Standard: “All three of these by-elections are in play.
“All parties will treat them as very serious contests.”
