A Labour feud between a suspended MP who accused the Number 10 'boy's club' of smearing him and the Chief Whip has burst into the open.
Outspoken MP Karl Turner tweeted a message from Jonathan Reynolds who threatened to block him if he didn't stop contacting him.
It came after the pair clashed following Prime Minister's Questions on Wednesday after the MP said there had been 'hostile briefings' about his mental health.
Mr Turner, who sits as the independent MP for Kingston upon Hull East, had the Labour whip removed in March after he criticised the Government over its plans to limit jury trials.
The former Labour MP had accused Sir Keir Starmer of allowing the 'lads in Number 10' to smear him over his mental health.
He told the Prime Minister: 'When I opposed his Government's plan to bring in single judge trials in England and Wales, I received hostile briefings and smears about my mental health from the lads in Number 10 Downing Street.
'The Chief Whip's shaking his head, but he knows about it.'
He asked if the PM had reflected on the briefings 'which he knew about, and he allowed to happen?'
Mr Turner, who sits as the independent MP for Kingston upon Hull East, had the Labour whip removed in March after he criticised the Government over its plans to limit jury trials.
Sir Keir replied: 'I want to be absolutely clear that nobody should be smeared in relation to mental health, nobody on any issue, whatever they may argue on any other issue, nobody.
'And I will do everything I can to make sure that that is the position.'
As Mr Turner walked past the front bench as the questions concluded, Mr Reynolds shouted: 'That was disgraceful.'
Justice Secretary David Lammy then came between the pair before Mr Turner left the chamber.
Following the dramatic exchange, Mr Turner tweeted a message he had received from the Chief Whip.
'As this is my personal number, I want to make clear you do not have permission to contact me on it ever again,' Mr Reynolds wrote.
'If you do not respect this, please note I will block your number.'
Mr Turner told the Mail: 'Since we won the general election it has not been unusual for Labour MPs to raise concerns about heavy-handed tactics from No. 10.
'Many colleagues have been briefed against including cabinet Ministers, and former Ministers are on record about briefings against them.
'Sadly I have also been on the receiving end of hostile briefings and smears. I notified every cabinet Minister including the PM in January that it was happening to me and made it clear that I would not be bullied.
'Many colleagues in the PLP have spoken about the chief whip being dismissive when they've raised concerns.
'The response from the chief whip to me says a lot more about him than it does me. I hope the PM is true to his word and will now act to make sure this stuff stops.'
Rosie Duffield, the former Labour MP who now sits as an independent after quitting the party, tweeted: 'This is a disgusting attitude towards lifelong, much respected LP [Labour Party] member, @KarlTurnerMP.
She said that the pair were free to speak about a culture of 'underhand workplace gameplaying' and said she was sad 'other colleagues can't speak up yet'.
A spokesman for the Chief Whip did not respond to requests for comment.