BORIS Johnson has been accused of promoting a Leave conspiracy theory about MPs collaborating with foreign powers to thwart Brexit.

The Prime Minister said there was a “legitimate question” about the origin of the emergency legislation passed by opposition MPs and Tory rebels to block a no-deal Brexit.

“No one knows by whose advice, or legal advice, it was drawn up,” he told BBC Radio 4.

In a separate interview on LBC Radio, in which he was read David Cameron’s description of him as “paranoid”, Mr Johnson also suggested the rash of recent stories about his private life were part of a “concerted effort to frustrate Brexit”.

His comments echoed Donald Trump's tendency to blame his problems on others conspiring against him.

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Last weekend’s Mail on Sunday newspapers reported Downing Street has launched a probe into alleged “collusion” between MPs and foreign governments.

Number 10 was said to suspect coordination between EU leaders and MPs behind the Benn Act, which will force the PM to request a Brexit delay if there is no deal by October 19.

Mr Johnson was asked about the story and a Downing Street source referring to MPs and “foreign collusion” in an interview with the Today programme.

He said: “I think there is a legitimate question to be asked about the generation of this SO24 [emergency procedure] legislation.

“It is a very interesting situation. We have Bills, an Act, the so-called Surrender Act which I’m afraid has massive consequences for the people of this country, will have massive consequences for the economy of this country were it to be effected...”

Asked if he thought “foreign governments” had been instructing MPs such as former Tory Attorney General Dominic Grieve and Oliver Letwin, he did not deny it.

He said: “We have no knowledge of how it was produced. It is not subject to normal parliamentary scrutiny. There are no Bill committees by which the processes by which this Bill can be generated can be invigilated.

“No one knows by whose advice, or legal advice, it was drawn up.”

“What I’m getting at is that nobody knows how these Bills are produced. With great respect to all my parliamentary colleagues, I do think we need to work out, as we go forward, how we’re going to scrutinise these things. They are a constitutional novelty to say the least.”

Mr Grieve has already rubbished the suggestion as “far-fetched”.

Former Tory MP Anna Soubry, who now leads the Independent Group for Change in the Commons, described the newspaper story on Sunday as “chilling evidence of the depths” to which Mr Johnson and his team would sink.

Reacting to his interview on Today, she tweeted: “To be very clear, Boris Johnson is in all seriousness suggesting on Today that legislation passed by Parliament which received royal assent sponsored by [Labour MP] Hilary Benn was written by ‘foreign powers’.

“This is a serious smear & he should be called to account #disgraceful.”

In his interview, the PM was also asked about his sister Rachel Johnson suggesting his character had been changed by power, and that he was “pursuing a deliberate strategy of making people feel their democracy had been stolen”.

He said: “I disagree with some people in my family.”

Asked when he had become an “angry, divisive man who smeared his opponents”, he said: “I don’t recognise that characterisation.”

He added: “I’m a pro-European. I love Europe.”

Later, in an interview with LBC’s Nick Ferrari at the Tory conference in Manchester, Mr Johnson denied any impropriety with US businesswoman Jennifer Arcuri or journalist Charlotte Edwardes.

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Ms Arcuri has reportedly told friends she had an affair with Mr Johnson while he was Mayor of London and she was receiving public funds from City Hall for her tech business.

Ms Edwardes said on Sunday that Mr Johnson has groped her in 1999, squeezing her inner thigh so hard she sat bolt upright as a lunch when he was Spectator magazine editor.

Asked how he would describe his relationship with Ms Arcuri, he said he did not want to elaborate, and said there was “no impropriety whatever” over financial issues.

He said a lot of the coverage of Ms Arcuri seemed to be generated by the current mayor of London, Labour’s Sadiq Khan, blaming him for a “lot of old nonsense”.

Asked if Mr Edwardes’s allegation was true, he said it was not. 

Asked why these stories were coming out just now, he said: “I’ll tell you why. I think there’s a very good reason, and that is that I’ve been tasked, one way or the other, to get Brexit done by October the 31st.

“And there are quite a lot of well-meaning and highly intelligent people who basically think that would be something they don’t want to see.

“I think that there is a concerted effort now to frustrate Brexit. I think that’s a mistake. 

“I think it would be very sad for our democracy if that were to happen.

“We need to get on and deliver the will of the British people.”

Asked if he was saying the stories about his private life were politically motivated, he said: “I don’t want to impugn people’s motives or to minimise the importance of the issue.

“All I can say if that that allegation is certainly not true, and I think generally if you asked why all this shot and shell is raining down on the Government, I think it’s because we’re going to get on and deliver Brexit by October 31.

“It’s an attempt possibly to distract from our domestic agenda.”

He refused to comment on whether he told former Tory PM David Cameron that Brexit would be “crushed like a toad beneath the harrow”.

Mr Ferrari also read an extract from Mr Cameron’s memoirs, in which he described Mr Johnson as “paranoid”, “full of jealousies” and “frankly a massive irritation”.

Mr Johnson said he had always got on well with Mr Cameron despite their ups and downs.