UKIP leader Henry Bolton has started a relationship with a 25-year-old model after splitting up with his wife.
Mr Bolton, 54, confirmed his relationship with Jo Marney in a letter to UKIP supporters on Wednesday.
Ms Marney describes herself in her Twitter profile as a “presenter, music journalist, model, actor, Brexiteer”.
He warned supporters to expect media coverage of a “change in my relationship status” but denied a “clandestine affair”.
Sources close to Mr Bolton insisted the relationship did not begin until after his split from his 42-year-old wife Tatiana Smurova-Bolton.
In a letter to supporters he said he expected his new relationship to be made public in The Sun newspaper.
A photo of him with Ms Marney was also published on the front page of the Daily Mail.
Mr Bolton said the story would “confirm that in recent weeks I’ve had a change in my relationship status” but “might also suggest (inaccurately) that this change has involved a clandestine affair with a young lady who happens also to be a member of UKIP”.
He said he had not “hidden” his new relationship and had made clear on social media that he had recently been spending time “with somebody who has become increasingly important to me”.
He continued: “I am in a new relationship and the media have latched on to that.
“However, whilst I fully accept that as a national political figure I can expect to be the subject of media attention, I also believe we’re all entitled to a certain degree of privacy.
“As such, I’ll be making no further comment on the matter.”
Ms Marney posted photographs of herself celebrating Christmas Day and Boxing Day with Mr Bolton.
He wrote on Twitter on New Year’s Day: “Myself and @Jo-Marney nearly run over by George Osborne in Covent Garden”.
He urged UKIP supporters not to allow the relationship to distract him or the party from their “vital mission”, promising a “significant ramping up” of political activity in the coming months.
The former army officer took over as UKIP leader in September.
He replaced Paul Nuttall, who quit following the general election, which saw the party’s vote share shrink to 1.8% from 12.6% in 2015.
Mr Bolton has three children, including a daughter who his wife gave birth to at London’s St Pancras Station in 2016, after going into labour on a train.