MPs cannot be stopped from calling Boris Johnson a “liar”, the House of Commons’ Deputy Speaker has said during a debate on Tory sleaze.

During a motion to censure the Prime Minister, Ian Blackford said Johnson and the truth had “always been strangers”.

He went on to give a number of examples, including nurses’ bursaries, the PM's statements on poverty levels and his previous comments on the Northern Ireland protocol.

The SNP Westminster leader opened up an Opposition Day debate as he delivered a scathing speech on the Prime Minister and his government.

READ MORE: Ian Blackford faces shouting and heckling while trying to point out Tory sleaze

Blackford said Johnson needed to be held to account, as he has been “up to his neck in scandals” since becoming Prime Minister two years ago.

Blackford drew heckling and shouting as he delivered his speech on the conduct of the PM.

Blackford said: “On the basis of all the evidence, I can only conclude that the Prime Minister has broken the six principles of public life, I can only conclude that the Prime Minister has demonstrated himself to be a liar.

“Let me finish on this point, I think there is a misguided sense on the Tory benches that they have gotten past the scandals of the past few weeks.

“The Prime Minister thinks that if he blunders on people might not forgive, but they will forget.

“Not for the first time the Tories are badly wrong and badly out of touch because they just don’t get that the depth of anger among the public is very real and is not going away.”

Plaid Cymru MP Liz Saville-Roberts interjected to say: “Do the members on the opposite side appreciate the damage that is done to be able to use the word liar in this place, [it] is now passed as fair comment and accepted and what that is doing to our democracy?”

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Deputy Speaker Dame Eleanor Laing replied to the Welsh MP: “Let us just be clear about that.

"It is preferable that such words not be used in this place but as I said before ... this is a very specific and particular motion and the right honourable gentlemen is examining the conduct of a member of this house, indeed the Prime Minister, therefore I cannot stop him from using the word that he has just used.

“I would prefer it if he put things in different terms but I don’t think the right honourable gentlemen has strayed past the rules - I think he is perfectly in order but it would be better if other members would not make comments such as those made by the honourable lady because what she said is not actually quite correct but please let us just keep it as moderate as possible.”

Also during the debate, Labour MP Dawn Butler said: “If we have a Prime Minister that comes to this House and fails to tell the truth, that is fundamental to how our democracy works in this country.”

She went on to call Johnson the "liar in the chief".

In July, Butler was suspended from the Commons after calling the PM a liar. However, Butler was allowed in this debate.