Jeremy Corbyn has been accused of considering calling the father of a senior Labour MP in an attempt to "bully" the politician into silence.
Labour whip Conor McGinn made the extraordinary claim that the party leader had considered using his father in an attempt to "apply pressure" on him following public criticism of Mr Corbyn.
Mr Corbyn's office dismissed the claims as "untrue" but St Helens North MP Mr McGinn accused the party leader of hypocrisy for talking about a "kinder, gentler politics" when "he had proposed using my family against me".
He said: "The leader of the Labour Party was proposing to address an issue with one of his own MPs by ringing his dad."
He suggested that Mr Corbyn considered calling his father, Pat McGinn, because he is a Sinn Fein councillor and thought they may "share a political affinity".
Mr McGinn said the leader had contemplated the action against him after a critical interview in May when he suggested that Mr Corbyn needed to understand that his Islington constituency in north London - often seen as a bastion of support for radical causes like unilateral nuclear disarmament - was "not like the rest of the country".
Mr McGinn said Mr Corbyn had initially asked for his resignation and considered sacking him after the comments in The House magazine but subsequently reconsidered.
But he added that he was later informed by colleagues in the Whips' Office about the proposal to call his father.
He said he had not made the incident public until now "because I find it shocking and embarrassing, and almost unbelievable".
In a statement, he said: "It transpired that Jeremy, in deliberations about how to respond to my interview, had said that he intended to ring my father to discuss it with him and ask him to speak to me about it.
"The leader of the Labour Party was proposing to address an issue with one of his own MPs by ringing his dad. Jeremy does not know my father so I can only presume that, because of the much-publicised fact that my father was a Sinn Fein councillor, Jeremy felt that they would share a political affinity and was proposing to use that to ask my father to apply pressure on me.
"Thankfully, others dissuaded Jeremy from taking this course of action. The call was not made, and it would not have been well-received."
Mr McGinn said he had decided to go public after watching an interview with Mr Corbyn in which he repeated his mantra of supporting a "kinder, gentler politics".
"I am afraid I could no longer tolerate the hypocrisy of him talking about a kinder, gentler politics when I knew for a fact that he had proposed using my family against me in an attempt to bully me into submission because he didn't like something I said."
Mr McGinn said he and other Labour MPs had been subjected to a "torrent of abuse and threats" from supporters of Mr Corbyn.
"In my constituency, a group of people gained access to my shared office building under false pretences and filmed themselves protesting outside the door of my office, in an incident that has been reported to the police," he said.
"They threatened to disrupt my surgeries and events I was attending, requiring me to have a police presence at those last weekend."
A spokesman for Mr Corbyn said: "What Conor McGinn is saying is untrue."