Former prime minister Boris Johnson deliberately misled Parliament over whether Covid lockdown rules were broken in No 10, a Privileges Committee investigation has found.

Boris Johnson committed “repeated contempts” of Parliament with his partygate denials that merited a 90-day suspension, a cross-party investigation has found.

The Privileges Committee’s recommended suspension for acts, including deliberately misleading MPs, would have paved the way for a by-election for the former prime minister if he had not resigned in anticipation.

Mr Johnson hit out at what he called a “deranged conclusion”, accusing the Tory-majority group of MPs he has repeatedly sought to disparage of lying.

He called the committee led by Labour veteran Harriet Harman “beneath contempt” and claimed its 14-month investigation had delivered “what is intended to be the final knife-thrust in a protracted political assassination”.

Mr Johnson quit the Commons last week after reading the report’s findings, meaning he will escape the immediate prospect of a sanction.

The recommended suspension far exceeded the 10-day threshold which, if approved by the wider House of Commons, could have led to a by-election in his Uxbridge and South Ruislip constituency.