Boris Johnson would have faced a 90-day suspension if he was still an MP, after an inquiry found he deliberately misled Parliament over lockdown parties.

In a damning report, MPs said the former PM had committed repeated offences with his Partygate denials.

The Privileges Committee’s suspension would have triggered a recall petition and possible by-election, had Mr Johnson not quit as an MP.

He dramatically stood down last week after seeing the committee’s findings.

Mr Johnson – who helped the Conservative Party win a landslide election victory under his leadership only three years ago – is the first former prime minister to have been found to have deliberately misled Parliament.

In a blistering statement attacking the committee, Mr Johnson said its members had reached a “deranged conclusion” that was “contradicted by the facts”.

He branded the committee, led by veteran Labour MP Harriet Harman, a “kangaroo court” and claimed its year-long inquiry had delivered “what is intended to be the final knife-thrust in a protracted political assassination”.

The seven-person committee, four of whom are Conservative MPs, has been considering whether Mr Johnson misled MPs about Covid-19 breaches in Downing Street and other government buildings during the pandemic.

When giving evidence to the committee in March, Mr Johnson staunchly denied misleading Parliament on purpose, in a stormy session.

But in its lengthy report, which runs to 106 pages, the committee concluded that Mr Johnson’s “personal knowledge of breaches”, combined with “his repeated failures pro-actively to investigate” them, amounted to “a deliberate closing of his mind” to the facts.

The committee focused on six gatherings between May 2020 and January 2021, and statements Mr Johnson made to Parliament about them.

The committee concluded that officials did not advise Mr Johnson that social-distancing guidelines had been followed at all times, despite him making the claim in the House of Commons.

In key evidence, one of Mr Johnson’s most senior officials, Martin Reynolds, said he advised the former prime minister against making the claim, questioning “whether it was realistic to argue that all guidance had been followed at all times”.

“Someone who is repeatedly reckless and continues to deny that which is patent is a person whose conduct is sufficient to demonstrate intent,” the committee said.

The committee’s report said “some of Mr Johnson’s denials and explanations were so disingenuous that they were by their very nature deliberate attempts to mislead” MPs.

Mr Johnson was also found to have breached confidentiality requirements when he criticised the committee’s findings in his fiery resignation statement last week.

“Mr Johnson’s conduct in making this statement is in itself a very serious contempt,” the report said.

The committee said the 90-day sanction was recommended because of repeated contempts, including:

The committee has also recommended that Mr Johnson should be stripped of the pass given to former MPs allowing them access to Parliament.

Two MPs on the committee wanted to go further and expel Mr Johnson from the Commons.

The SNP MP, Allan Dorans, proposed an amendment to the report, seeking a ban, but the four Conservative MPs on the committee voted against this.

The report will be debated by MPs, with a vote held on whether to approve the findings on Monday.

MPs are expected to approve the report, after Commons leader Penny Mordaunt said Tory MPs would not be ordered to vote against it.

So far, only a handful of Conservative MPs have openly criticised the report, including Johnson loyalist and former culture secretary, Nadine Dorries.

In a tweet, Ms Dorries claimed the report had “overreached” and said any Tory MP who voted to approve it was “fundamentally not a Conservative”.

But Labour’s deputy leader, Angela Rayner, said the committee had “gone off the evidence” to reach “a very damning conclusion”.

She said Mr Johnson was a “disgraced prime minister” who “shouldn’t be anywhere near Parliament”.

The Liberal Democrats have called for Mr Johnson to be stripped of the £115,000 annual allowance available to former prime ministers to run their office.

“This damning report should be the final nail in the coffin for Boris Johnson’s political career,” the party’s deputy leader, Daisy Cooper, said.

The committee’s report was met with disdain by Mr Johnson, who repeated his defence at length in a bitter parting shot.

He said he had been warned the committee was driven by “the sole political objective of finding me guilty and expelling me from Parliament”.

He echoed many of the assertions he made in front of the committee in March, including his claim that he believed all of the events he attended were “lawful” and “required by my job”.

On the charge he deliberately misled Parliament, Mr Johnson said this was “rubbish” and based on “a series of things that are patently absurd”.

He said perhaps “the craziest assertion of all is the committee’s Mystic Meg claim that I saw the Dec 18 event with my own eyes”.

Mr Johnson is referring to a gathering attended by dozens of staff in No 10 Downing Street’s press office ahead of the Christmas break.

In its report, the committee concluded it was “unlikely” that Mr Johnson would not have been aware of the party, given he had passed the press office en route to his flat at the time.

“How do they know what I saw?” Mr Johnson said. “What retinal impressions have they somehow discovered, that are completely unavailable to me?”

Deriding the committee as incompetent, Mr Johnson snubbed its report as a “charade”.

“The terrible truth is that it is not I who has twisted the truth to suit my purposes,” Mr Johnson said. “It is Harriet Harman and her committee.”

The lockdown parties at the heart of the committee’s report first came to public attention in newspaper reports at the end of 2021.

The reports exploded into a long-running scandal that dogged Mr Johnson’s premiership and stoked discontent among his ministers, who forced him to resign as prime minister last year.

An internal inquiry into the parties was led by senior civil servant Sue Gray, and a Metropolitan Police investigation resulted in multiples fines for breaches of Covid rules.

Mr Johnson was fined by police for breaking Covid rules in 2020 – making him the UK’s first sitting prime minister to be sanctioned in such a way.

Meanwhile, Liberal Democrat Scottish affairs spokesperson Christine Jardine MP said Boris Johnson caused immeasurable damage to public trust in politics and that people are sick of Conservative sleaze.

Liberal Democrats have today called for Rishi Sunak to strip Boris Johnson of his ex-PM allowance. Former Prime Ministers are entitled to claim up to £115,000 a year to fund office costs for life.

Ms Jardine said:  “People across Scotland and the UK are sick of the sleaze, chaos and law-breaking that has come to define the Conservative party.

“This report should be the final nail in the coffin for Boris Johnson’s political career and the Scottish Conservatives who endorsed and defended him.

“Rishi Sunak must cut off Johnson’s ex-Prime Minister allowance to stop him milking the public purse for his own personal gain. Anything less would be an insult to bereaved families who suffered while Boris Johnson lied and partied.”