A PR worker whose firm union boss Len McCluskey accused of "orchestrating" Labour MPs' "coup" against Jeremy Corbyn has claimed he has received a death threat telling him he will be "coxed" - an apparent reference to Jo Cox.
Labour MPs have lined up to condemn the threat to Kevin McKeever, a partner at Portland Communications and a former parliamentary candidate for the party, as "disgusting", "disgraceful" and "a betrayal for all we stand for".
It comes after Unite general secretary Mr McCluskey accused Portland of being a "sinister" Blairite organisation which has been "critically involved" in Labour MPs' attempts to make Mr Corbyn stand down as leader, in apparent reference to loose allegations made by online blog The Canary.
Mr McKeever has now posted a photo of the alleged death threat on Facebook and Twitter.
The typed threat reads: "hello comrade
"we've watched you leave this building
"we've watched you on the strand
"your blood is the price of your treachery
"prepare to be coxed
It is thought the final sentence is a reference to Mrs Cox, the Labour MP who was killed after being shot and stabbed in Birstall, West Yorkshire, on June 16.
Alongside the picture, Mr McKeever posted a statement, which read: " Many of you will have read posts on a blog suggesting a link between me, my workplace and the moves by Labour MPs in Parliament. They have no basis in truth.
"I've made my personal views clear on our party's leadership.
"I have, however, been silent for the past few days due to a hand-delivered death threat, suggesting I should be 'coxed', a reference to the murder two weeks ago of Labour MP, Jo Cox.
"On the advice of the police and in the interests of the personal safety of me, my family, I will not be commenting further.
"We have a Labour Party to return to after this mess. I hope we all reflect."
Mr McCluskey made reference to Portland during a television interview on Sunday.
Referring to MPs who want to remove Mr Corbyn, he told BBC One's Andrew Marr Show : "I think they have been seduced by sinister forces in play here.
"Well, if the BBC want to do an investigatory programme of a company called Portland then feel free to do so.
"This is a PR company with strong links to Tony Blair, right-wing Labour MPs, who have been critically involved in this orchestrated coup."
Labour MPs lined up to condemn the alleged death threat.
Mr Corbyn's former leadership rival Liz Kendall tweeted: " Disgraceful. Cowardly. And a betrayal of all we stand for. Kevin please know #wearewithyou".
Lucy Powell, who quit the shadow cabinet as part of a wave of resignations designed to put pressure on Mr Corbyn to stand down, tweeted: " This is disgusting. This vile (behaviour) has to be stopped."
Shadow minister without portfolio Jon Ashworth, who is still serving in Mr Corbyn's shadow cabinet, tweeted : "I'm sending my solidarity to @kevinmckeever - hate will not win".
MP Wes Streeting tweeted: " This is an absolutely disgusting turn of events. Death threats: the new politics? Just grim."
It comes after Mr Corbyn and deputy leader Tom Watson held separate talks with Mr McCluskey in an attempt to resolve the crisis at the top of the Labour Party.