Ukip has claimed a Conservative parliamentary candidate has defected to the party. But the Tories say Mike Whitehead, who is standing in the Hull West and Hessle constituency, was sacked last week.
Nigel Farage described the news as “another hammer blow to Tory pretensions in the north of England”.
But a Conservative Party spokesman dismissed the party’s announcement as “cynical, misleading and utterly calculating to try and score political points”.
Mr Whitehead is a councillor on East Riding Council.
He said he was “disgusted” with the behaviour of the ruling Tory group in East Yorkshire and the “wilful refusal” of the Conservative party to intervene at a national level.
He insisted the “secretive” council needed to be “opened up” and made more transparent.