Alistair McAlpine has denied "wholly false" child abuse allegations levelled at him online, after deciding he must "publicly tackle these slurs and set the record straight".
The former Conservative party treasurer, who now lives in Italy, released a statement in which he said it was "obvious" that there were a "substantial number of people" who had "reasonably inferred that the allegation of guilt… attached to me".
He said he had found himself at the centre of a "media frenzy" in which his name had been "for all practical purposes linked" with allegations of child abuse at a children's home in Wrexham in the 1970s and 1980s.
"I therefore have decided that in order to mitigate, if only to some small extent, the damage to my reputation I must publicly tackle these slurs and set the record straight," he wrote.
"In doing so I am by no means giving up my right to sue those who have defamed me in the recent past or who may do so in the future and I expressly reserve my rights to take all such steps as I and my solicitors consider necessary to protect my interests."
Child abuse victim Steve Messham had claimed he had been sexually abused by a senior member of the Conservative party, prompting the wave of speculation about the identity of the man.
McAlpine insisted he had only ever been to Wrexham, where the abuse is alleged to have taken place, once.
He was accompanied on the trip "at all times" and never visited "any children's home, reform school or any other institution of a similar nature", he said.
North Wales police's chief constable Mark Polin and Keith Bristow, the National Crime Agency, have begun investigating the fresh allegations. McAlpine said he was prepared to cooperate with their work.
"Although I live in Italy and have done so for many years and although I am in poor health, I am entirely willing to meet Mr Polin and Mr Bristow in London as soon as can be arranged so that they can eliminate me from their inquiries and so that any unwarranted suspicion can be removed from me," he stated.
"I wish to make it clear that I do not suggest that Mr Messham is malicious in making the allegations of sexual abuse about me.
"He is referring to a terrible period of his life in the 1970s or 1980s and what happened to him will have affected him ever since.
"If he does think I am the man who abused him all those years ago I can only suggest that he is mistaken and that he has identified the wrong person."
McAlpine said he viewed reports of child abuse as "abhorrent" and made clear he believes the victims had been "horribly violated".
"I have absolutely no sympathy for the adults who committed these crimes," he said.
"Those who have been convicted were deservedly punished and those who have not yet been brought to justice should be as soon as possible."