MPs have approved a report rebuking some of Boris Johnson’s closest allies for attacking and seeking to undermine an investigation into whether he deliberately misled parliament over the partygate scandal.

The Privileges Committee, which investigated the former prime minister’s partygate lies, highlighted comments by eight Conservative politicians and claimed they were part of a co-ordinated attempt to undermine its work.

Those named included former cabinet ministers Jacob Rees-Mogg, Priti Patel and Nadine Dorries.

MPs approved the report without the need for a formal vote.

The motion before the House of Commons also sought to make clear about how MPs should behave when a Privileges Committee inquiry is taking place.

Commons Leader Penny Mordaunt said the report was an “exceptional situation” and not part of the usual “cut and thrust of politics”.

Introducing the motion, she told the Commons: “I hope colleagues who have been named will reflect on their actions.

“One of the most painful aspects of this whole affair is that it has involved animosities between colleagues, and colleagues of the same political hue.

“But I know of at least one member named in the report who has taken the time to speak with regret to some other members of that committee and I applaud them for doing so.

“I hope that some speeches we might hear this afternoon will acknowledge that obligation we have to one another as colleagues.

“If Castlereagh and Canning could adopt polite civility after fighting a duel, I live in hope that today will be the end of this sorry affair.”

Mordaunt’s final remark referred to former prime minister George Canning, who as foreign secretary quarrelled with the war minister over the deployment of troops.

Robert Stewart, the “Lord Castlereagh”, challenged Canning to a duel which was fought on September 21, 1809.

The Privileges Committee ultimately triggered Johnson’s resignation from Parliament in protest at its recommendation that he should face a lengthy suspension for misleading the Commons with his denials of lockdown-busting parties in Downing Street.

Johnson’s supporters frequently attacked the Labour-led but Tory-majority committee as a “witch hunt” and “kangaroo court” – with the former prime minister found to be complicit in the campaign against the panel investigating him.

Other MPs quoted in the report included Conservatives Mark Jenkinson, Michael Fabricant, Brendan Clarke-Smith and Andrea Jenkyns, while Conservative peer Zac Goldsmith was also named.

Rees-Mogg was among those named to use the debate to push back on the report.

The former business secretary said: “There are some issues with this report, I think beginning, as it happens, with its title, ‘co-ordinated campaign of interference’… there is no evidence that it was co-ordinated.”

Asked by Labour MP Angela Eagle if he would like to apologise to the committee members for calling them “marsupials”, Rees-Mogg said: “I have absolutely no desire to impugn the integrity of individual members of the committee, some of whom I hold in very high regard.”

He also told MPs: “I’ve always thought it is important to get on well with people and to be courteous to them … across the House. But that doesn’t mean that one can’t criticise them.

“And it was legitimate, and it is legitimate, to question the position of the chairman of the committee.”

Labour’s Harriet Harman, who chaired the Privileges Committee, said: “Our special report makes it clear that it’s not acceptable for members fearing an outcome which they don’t want to level criticisms at the committee, so that in the event the conclusion is one they don’t want they will have undermined the inquiry’s outcome by undermining confidence in the committee.”

Jenkinson was among those Conservative MPs to clash with Harman in the chamber, saying his tweet did not refer to the committee and the “context of the Twitter thread was clear”.

Harman said Jenkinson had called the committee a “witch hunt”, with the Tory MP suggesting Harman might have “inadvertently misled the House”.

Harman replied: “If he’s saying, which he has, that he doesn’t believe the Privileges Committee inquiry into Boris Johnson was a witch hunt then I very warmly welcome the fact he’s said that and appreciate it.”

Fabricant acknowledged that calling the Privileges Committee a “kangaroo court” was wrong.

He had earlier said he stood by the comments he made that serious questions will have to be answered in relation to the committee’s procedure.

Patel told MPs: “I do feel that the assertions that have been made and the claims that have been made in this special report are wrong and cannot be substantiated by the so-called evidence that has been produced and published.”

Conservative former minister Jenkyns said: “Actions of this committee could mark a dangerous precedent, a slippery slope.”

But Conservative MP Julian Lewis said those who accepted the process should also accept the result, adding: “If you’re not prepared to accept the verdict of the umpire, don’t play cricket.”

Commons Speaker Sir Lindsay Hoyle did not select a Liberal Democrat amendment which sought to refer Johnson loyalists back to the Privileges Committee to decide if their conduct amounted to contempt.