A leading supporter of Liz Kendall has accused her rivals for the Labour leadership of conducting a "smear" campaign against her after he was forced to deny they were in a relationship together.
John Woodcock has said the highly personal rumours circulating in Labour circles were "totally unacceptable" and needed to stop.
It is understood the MP, who is recently divorced, decided to speak out after being contacted by two different journalists who told them the claims came from the campaign of one of her leadership rivals.
"People who are spreading these rumours about Liz and me need to remember how much damage these acts of smear can do," he told The Daily Telegraph.
"This is clearly being done systematically, to damage Liz's campaign. It is totally unacceptable and that is why I have decided to talk about this publicly.
"It is hurtful for my family, and it is designed to make things difficult for Liz."
Mr Woodcock - who informed Ms Kendall's campaign team that he intended to go public - said the claim that had been made was "not true, has never been true and would never be true".
He said: "This has given me a small insight into the kind of difficulty so many women come across, when it is said that they are only where they are because they are sleeping with someone or someone fancies them."
Ms Kendall's campaign has previously hit out after complaining that rivals had sought to damage her by highlighting the fact that the shadow care minister did not have children.