The husband of cleared solicitor Sally Clark said he thought it was "a sick joke" when a senior doctor accused him of murdering their two sons.
Mr Clark felt he was being 'branded a double murderer'
Steve Clark was giving evidence against paediatrician Professor David Southall at General Medical Council hearing in Manchester.
Professor Southall contacted police after seeing Mr Clark interviewed on TV while his wife served life in prison.
He could be struck off if he is found guilty of professional misconduct.
Sally Clark was convicted in 1999 of murdering her two sons Christopher and Harry.
However, her conviction was quashed when new medical evidence showing the babies died of natural causes was accepted by a second appeal hearing in January, 2003.
A Channel 4 Dispatches documentary, broadcast in April 2000, featured an interview with Mr Clark, in which he described a nosebleed suffered by their first baby Christopher in a London hotel just 10 days before he died in December 1996.
Professor Southall saw the programme and told police it was his view that it was Mr Clark, rather than his wife, who had killed Christopher and Harry.
Mr Clark was interviewed by social workers, and the courts appointed another paediatrician to review Professor Southall's claims.
The second paediatrician did not agree with Professor Southall and the matter went no further.
Mr Clark then lodged a complaint against the professor with the GMC in London.
'Life in chaos'
Mr Clark told the GMC he had just got his third son back from foster carers and was trying to bring him up as a single father when the allegations were made.
He said: "I was quite stunned. For the last two and a half years I felt my family had been attacked by the full force of the state.
"I'd lost my son, who'd been taken away from me, and had lost my wife.
"My life was in chaos at that point. Everything I had worked for had been taken away from me."
He said his initial reaction was that it was "quite astounding" that a senior paediatrician could come to these conclusions "largely on watching a TV programme".
Mr Clark said the professor had made the claims without having talked to health professionals or looking at records relating to his sons' deaths.
"Initially I thought - is this some sort of sick joke?
"Then I realised it was not, it was deadly serious."
'Branded a double murderer'
Mr Clark, who feared he could have been arrested over the murders, adding: "My son could be taken into care, even taken out of the family, and I would never see
He added that he felt he was being "branded a double murderer by a very senior and well respected consultant paediatrician".
When asked by Richard Tyson, for the GMC, if he had killed his sons Christopher and Harry, Mr Clark said: "No I did not."
He added that he had always believed his wife, Sally, was innocent of the murders.
Guy Mitchell, a consultant social worker who acted as guardian to the Clarks' third child, told the GMC that Mr Clark's care of the child at the time the allegations were being made was "excellent".
He said he believed there was a "fatal flaw" in Professor Southall's allegatons, because Mr Clark was at an office party when Christopher died.
But he added: "It has to be right that the child protection system encourages people to talk about children they consider to be at risk."
Professor Southall, based at North Staffordshire Hospital in Stoke, is one of Britain's leading experts on Munchausen's Syndrome By Proxy, a condition which apparently drives parents to harm their own children in order to win attention.
He admits contacting Cheshire police after watching the programme, and forming the view that Steve Clark had deliberately suffocated his son.
However, he denies that his behaviour was irresponsible or an abuse of his professional position and he denies serious professional misconduct.