Sir Keir Starmer has blamed Boris Johnson for the group of antivax protesters who accosted him, claiming the Prime Minister knowingly pedalled “a conspiracy theory of violent fascists”.

The opposition leader was targeted by a mob near Parliament, facing allegations of “protecting paedophiles” and chants about the sex offender from protesters.

It came just days after the Prime Minister accused Keir Starmer of having “used his time prosecuting journalists and failing to prosecute Jimmy Savile”.

In an interview with The Times, Sir Keir said Mr Johnson had placed him in danger by using a “deliberate slur without any basis in fact”.

Hereford Times: Labour leader Sir Keir Starmer during a visit to the Prince's Trust South London Centre in London. Photo via PA.Labour leader Sir Keir Starmer during a visit to the Prince's Trust South London Centre in London. Photo via PA.

'Boris Johnson incited mob with Jimmy Savile conspiracy theory'

“The PM knew exactly what he was doing. It is a conspiracy theory of violent fascists that has been doing the rounds for some time,” Sir Keir said.

Mr Johnson last week accused his rival of failing to prosecute notorious paedophile Jimmy Savile while he was director of public prosecutions.

“I have never been called a paedophile protector before. That happened yesterday for the first time in my life,” Sir Keir said.

“If others want to argue that this is unconnected with precisely what the Prime Minister said one week before then let them make that case. But they’ll never persuade me that there is no link.

“It’s not about me, it’s the way we conduct our politics. I don’t want to see us go down the route that this potentially takes us.”

Earlier, Sir Keir’s spokesperson said he was “fine” after the incident.

A spokesman for the opposition leader told reporters: “He was back at his desk straight after. Police did their job.

“Obviously these things look sort of rougher on the camera often than they are.

“But, as I say, police did a good job, he was back at his desk afterwards and he was off playing five-a-side football that night as normal.”

A host of Conservative and opposition MPs have called for Mr Johnson to apologise for what was branded a “scurrilous accusation” against Sir Keir.

The Prime Minister’s official spokesman acknowledged his original words last week in the Commons were “capable of being misconstrued” and said that was why he subsequently issued a “clarification”.

Hereford Times: Photo via PA. Prime Minister Boris Johnson leaves 10 Downing Street, London, to attend Prime Minister's Questions at the Houses of Parliament. Photo via PA. Prime Minister Boris Johnson leaves 10 Downing Street, London, to attend Prime Minister's Questions at the Houses of Parliament.

“The Prime Minister clarified his remarks last week to make clear he was not suggesting Keir Starmer was individually responsible for the Savile decision,” the spokesman said.

He added: “I think the Prime Minister was making a political point about taking responsibility for organisations as a whole.”

Fact check: Was Sir Keir Starmer actually responsible for failing to prosecute Jimmy Savile?

Although Sir Keir was head of the Crown Prosecution Service in 2009 when a decision was taken not to prosecute Savile, he had no personal involvement in the deliberations.

Nazir Afzal OBE - one of the UK's top solicitors with experience in the legal areas of child sexual exploitation - discussed the Jimmy Savile conspiracy about Sir Keir Starmer with his Twitter followers.

Mr Afzal said: "Starmer had NOTHING to do with Savile case. When he became aware HE began fixing failures that let all victims down I led the response. He left office with highest conviction rate in history."

Labour said Monday’s incident occurred when Sir Keir, who was accompanied by shadow foreign secretary David Lammy, was walking back from the Ministry of Defence after a briefing on the situation in Ukraine.

Mr Johnson tweeted on Monday evening that the “behaviour directed” at the Labour leader was “absolutely disgraceful”.