BORIS Johnson will face an investigation into whether he lied to parliament.

The Prime Minister will now be referred to the privileges committee – a powerful group of MPs which can find Johnson in contempt of parliament if they conclude he misled the House.

MPs debated whether to refer Johnson to the privileges committee for nearly five hours and were unusually allowed to refer to the Prime Minister as a liar – despite convention banning the word.

READ MORE: Ian Blackford 'feels sorry' for 'spineless' Douglas Ross as career 'ruined' by PM

The investigation will begin following the conclusion of the Metropolitan Police investigation into the extent of lawbreaking in Downing Street during lockdown.

So far, more than 50 fixed penalty notices have been issued to politicians and staff at the centre of government – including the Prime Minister, his wife and the Chancellor.

The committee will have the power to request documents and photographs as the Sue Gray investigation did.

Labour MP Chris Bryant stepped down as chair of the committee before the vote, in a bid to make the investigation more likely, as Tory MPs would not be able to accuse it of being biased.

It will mean the partygate scandal is prolonged and some Tory MPs’ patience with the Prime Minister is wearing thin.

In a blow to Johnson, former minister Steve Baker, an influential organiser on the Tory benches, said the Prime Minister “should be long gone”.

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Johnson, who dodged the debate today because he is on a visit to India, insists he has “nothing to hide”.

Ian Blackford, the SNP’s leader in Westminster, called the Prime Minister a habitual and repeated liar.

He told MPs: “This is who the Prime Minister is. It is who he has always been.

“As Prime Minister - he has done exactly what it said on the tin.”

And he delivered a devastating verdict on Douglas Ross who he said had had his career "ruined" by the Prime Minister.

Blackford added: "I have to admit, when I reflect on the position of the Scottish Tory Leader - my real reaction is something that I know he’ll appreciate far, far less. I actually feel sorry for him.

"Because he is by no means the first person to have his career ruined by this Prime Minister.

"That particular pile of people is a mountain high by this stage.

"Because ultimately everybody – and I mean everybody – is eventually thrown under the Boris bus."

Labour leader Keir Starmer said the Prime Minister had tried to “cover up his misdeeds” by taking advantage of the Commons convention not to call someone a liar.

“The Prime Minister has stood before this House and said things that are not true, safe in the knowledge that he will not be accused of lying because he can’t be,” he said.

“He has stood at that despatch box and point blank denied rule-breaking took place, when it did.

“As he did so, he was hoping to gain extra protection from our good faith that no Prime Minister would deliberately mislead the House.”

Scotland Yard’s investigation into the parties in Downing Street and Whitehall during England’s lockdowns in 2020 and 2021 is continuing, although May 5’s local elections mean no announcement about further fines will be made until after polling day.

READ MORE: Read Ian Blackford's devastating speech on 'liar' Boris Johnson in full

The Prime Minister’s aides are braced for him to receive multiple fines, having already been handed one fixed-penalty notice for a gathering on his 56th birthday.

He is thought to have been at six of the 12 events under investigation by Scotland Yard.

The motion voted on by MPs states Johnson’s comments “including but not limited to” four separate remarks in the Commons “appear to amount to misleading the House”.

He also faced fierce criticism from William Wragg, the Tory chair of the powerful Public Administration and Constitutional Affairs Committee, who has called for a no-confidence vote in the Prime Minister.

He told MPs: “I cannot reconcile myself to the Prime Minister’s continued leadership of our country and the Conservative Party.

“There can be few colleagues on this side of the House I would contend who are truly enjoying being Members of Parliament at the moment.

“It is utterly depressing to be asked to defend the indefensible. Each time part of us withers.”