BORIS Johnson has been urged to retract a “disgusting slur” against the Labour leader.

The Prime Minister claimed Sir Keir Starmer had been responsible for failing to prosecute notorious paedophile Jimmy Savile while he was director of public prosecutions in England and Wales.

Mr Johnson made the claim during a speech in the Commons under parliamentary privilege, which means the Labour leader is unable to take legal action for example for defamation.

As he battled to defend himself from the partygate row yesterday, Mr Johnson claimed Sir Keir “used his time prosecuting journalists and failing to prosecute Jimmy Savile”.

Asked about the remarks this morning on the radio, Mr Johnson’s deputy Dominic Raab said he could not substantiate the claims and was “certainly not repeating” them.

The Prime Minister’s official spokesman said this afternoon that he stood by the remarks he made, but he also refused to repeat the comments without the protection of parliamentary privilege.

He said: “As a civil servant it wouldn’t be right for me to repeat something which relates to a political aspect of the Prime Minister’s work.”

Fact-checking by Reuters and Full Fact has found “no evidence” to support the claims, and Sir Keir has described them as a “slur peddled by right-wing trolls”.

Tory peer Lord Ian Duncan and SNP Westminster Leader Ian Blackford are among those who have called for Mr Johnson to retract the comments.

Mr Blackford said the remarks were “a slur on the Labour leader, and yet another example of the character of this Prime Minister”.

Lord Duncan, who today called for Mr Johnson to resign as PM, told the Herald he thought the comments should be withdrawn and suggested Sir Keir could “complain formally” to “initiate an investigation”.

Labour’s shadow Scottish Secretary Ian Murray said the comments were “completely fabricated and untrue”.

He said: “The Cabinet won't defend the PM because he has lied again.

“It is a completely fabricated and untrue slur and he should apologise.

“Every day Boris Johnson demeans the office of PM and he should just take his lies and slurs and resign for the sake of the country."

Earlier today, Tory former chief whip Julian Smith also called on the remarks to be retracted, saying: “The smear made against Keir Starmer relating to Jimmy Savile yesterday is wrong and cannot be defended. It should be withdrawn.

“False and baseless personal slurs are dangerous, corrode trust and can’t just be accepted as part of the cut and thrust of parliamentary debate.”

Commons speaker Sir Lindsay Hoyle said he did not think the comments were “appropriate”, adding: “While they may not have been disorderly, I am far from satisfied that the comments in question were appropriate on this occasion.

“I want to see more compassionate, reasonable politics in this House and the sort of comment can only inflame opinions and generate disregard for this House.

“I’ve got to say I want a nicer Parliament, the only way we can get a nicer Parliament is being more honourable in the debates we have.”