Wife of British prime minister; Carrie Johnson has insisted she “plays no role in government” and has been targeted by “enemies” of the prime minister in what her spokesperson described as a “brutal briefing campaign”.

Boris Johnson’s wife issued a rare statement through her spokesperson on Sunday evening, after a Cabinet minister suggested she was coming “under scrutiny in a way that perhaps other prime ministers’ spouses weren’t” in the past.

Mrs Johnson’s role in her husband’s premiership has faced intense scrutiny.

Lord Ashcroft, writing in the Mail, said his research had suggested her “behaviour is preventing him (Boris Johnson) from leading Britain as effectively as the voters deserve”.

But allies have dismissed the criticism as sexist, and a spokesperson for Mrs Johnson said on Sunday: “Yet again Mrs Johnson has been targeted by a brutal briefing campaign against her by enemies of her husband.

“This is just the latest attempt by bitter ex-officials to discredit her. She is a private individual who plays no role in government.”

But Guto Harri, the newly appointed director of communications at Downing Street, speaking on the BBC Newscast podcast last week, said the episode “raises that other spectre that never goes away of who is influencing him (the PM) and we all know who’s being accused of doing so on this occasion, because she is an animal lover more than him really”.

Asked if he was referring to Mrs Johnson, he replied: “You said it, not me.”

Dominic Cummings, the prime minister’s former chief aide, has made clear he was no fan of Mrs Johnson, and said she had wanted to “get rid” of him from No 10.

He alleged she was at one point “trying to change a whole bunch of different appointments at Number 10 and appoint her friends to particular jobs”.

Over the weekend, a biography of the 33-year-old mother of two, by Tory peer Lord Ashcroft, was serialised in the Daily Mail and Mail On Sunday, which sought to look at her alleged influence on Mr Johnson’s decision-making. However after his allies dubbed Mrs Johnson “Princess Nut Nut” in press briefings, David Cameron’s wife Samantha said the attacks were “sexist”.

She said: “In my view, your husband or partner is the prime minister, they’re quite able to take decisions themselves, they have a huge team of advisers.

“And so the idea that it’s the wife, that you’re somehow influencing them over and above what they think or what advice they’re getting from their team, I think it’s kind of demeaning, really, for the Prime Minister.”

Labour MP Jess Phillips has previously labelled criticism of Mrs Johnson as “sexist” and “ageist”.

She said there had been briefing by “men who don’t like Carrie Symonds because they don’t have the influence they want to have”.

She added: “I have literally seen no evidence in my day-to-day life that Carrie Symonds (has too much influence). In some regards, maybe I’d like her to have more – she’s quite a feminist.”