Boris Johnson will reportedly be found on Wednesday to have deliberately misled MPs over parties in Downing Street during the pandemic.

The Privileges Committee has rejected the former prime minister’s defence that senior officials advised him Covid rules and guidance had been followed in No 10, according to the Times.

But Mr Johnson – who resigned on Friday after receiving the group’s report – struck a defiant tone, quoting Arnold Schwarzenegger as he told the Daily Express: “I’ll be back.”

The ex-MP accused the committee of “bias” and likened it to a “kangaroo court” in a furious 1,000-word exit statement after receiving a draft of its findings.

The panel, chaired by Labour MP Harriet Harman but with a Conservative majority, found that one of his most senior officials in fact warned him against claiming social distancing guidelines were followed at the gatherings, the Times reported.

According to the paper, Martin Reynolds, Mr Johnson’s principal private secretary at the time, advised him in December 2021 that he should remove a claim from a statement to the Commons that “all guidance had been followed at all times”.

The aide reportedly questioned “whether it was realistic to argue that all guidance had been followed at all times”.

Mr Johnson is said to have removed the line from his opening statement, but repeated the assertion during a debate later – which the committee reportedly views as evidence MPs were deliberately misled.

But 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 Mr Schwarzenegger’s cyborg character in the 1991 movie Terminator 2: Judgment Day.

That reference similarly left the door open for a possible comeback, but the former Uxbridge and South Ruislip MP remained on the back benches until quitting the Commons on Friday.

The committee’s report will find that Mr Johnson would have been sanctioned with a suspension of more than 10 days – enough to trigger a by-election, according to the Times.

It is also expected to make clear that criticism of the committee should be considered contempt of Parliament after Mr Johnson and his allies dismissed the inquiry as a “witch hunt”.

Downing Street defended the group for having done “exactly what Parliament asked them to do” while senior Tory MP Damian Green said it was “monstrous” the committee was being attacked for their work.