Ukip announced Mike Whitehead had defected but the Conservatives said he was sacked last week as the candidate for the Hull West and Hessle constituency.
Nigel Farage described the news as “another hammer blow to Tory pretensions in the north of England”, but a Conservative Party spokesman dismissed Ukip’s announcement as “cynical, misleading, and utterly calculating to try and score political points”.
He added: “This man is not our candidate for Hull West and Hessle. He was sacked last week.
“He refused to support the local Conservative council candidate and so we wrote to him last week to say that his position was untenable and he could not stand for us at the general election. We were already selecting a new candidate for this constituency.”
Mr Whitehead, a councillor on East Riding Council in Yorkshire, has now admitted he was informed on Wednesday that his candidacy would be removed if he did not stand aside from his intention to run in the local elections.
He told BBC Radio 5 Live: “The Conservative Party took a pre-emptive strike because they knew it was coming.”