Nigel Farage has said he would "probably" stand again in the Kent constituency he fought at the 2015 general election if a fraud investigation leads to a by-election.
Kent Police and the Electoral Commission are investigating whether the Conservatives broke the law by failing to properly declare expenses related to the 2015 campaign.
According to the Mail On Sunday, Mr Farage's election strategist Chris Bruni-Lowe has passed a dossier to police containing details of computer logs accessed by Ukip's only MP Douglas Carswell, who defected to the party from the Conservatives.
It claims that Mr Carswell passed details about local voters to the Tories to help them defeat Mr Farage - an allegation he strongly denies.
Mr Farage, who has a long-running feud with the Clacton MP, said there was "evidence" that Mr Carswell downloaded information but there was nothing to prove what he did with it.
The former party leader told BBC One's Sunday Politics: "I don't know anything about the dossier.
"I am actually quite dubious as to whether this dossier exists at all. I think perhaps the newspapers have got this wrong.
"Were there concerns about the downloading of data that took place from that constituency? Yes. But beyond that we don't know anything.
"We have evidence that Mr Carswell downloaded information. We have no evidence of what he did with it."
The South Thanet seat was won by Tory Craig Mackinlay.
Asked if he would stand in a by-election prompted by the investigation, Mr Farage replied: "I probably would."
Mr Carswell said: "I am not commenting but I very strongly deny it."