Jeremy Corbyn's right hand man has accused supporters of Labour leadership challenger Owen Smith of threatening to split the party.
Shadow chancellor John McDonnell claimed that backers of Smith are warning the party will inevitably divide if Corbyn retains the party leadership.
Speaking on BBC radio earlier, McDonnell called on Smith to denounce a split.
“I just think this is a wrong tactic in a leadership election,” McDonnell told the Today programme.
“Effectively the message that’s coming across from some of Owen Smith’s friends is that you either vote for Owen Smith or we’ll split the party."
“That’s a threat and I don’t think that’s acceptable and I don’t think that’s what Owen wants either.”
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It comes after Smith told the Guardian that the party was “teetering on the edge of a precipice”.
“The party that has been here for 116 years as the greatest source of social and economic justice could be bust apart and disappear,” Smith said.
Smith has previously accused McDonnell of stating that Labour should divide “if that's what it takes”, a claim that has been backed by MPs including Smith's campaign chair Kate Green.
But today, McDonnell insisted: “I don't think I did say that, I don't recall that.”
He added: “It was in the context of basically a group of MPs, including Owen Smith, came in to tell Jeremy Corbyn to resign, and Jeremy said, 'No, I have a mandate from the members, I'm not going to let them down'.”
The comments come ahead of a speech from Corbyn in Dagenham, in which the Labour leader will present 10 pledges to “rebuild and transform” Britain.
Speaking at the London East Business and Technical Park, Corbyn is expected to say that few Britons enjoy prosperity in the UK, and will promise a £500bn programme of investment.
He will also map out plans for a £250bn national investment bank, backed up by regional development banks.
"We will deliver the transport and communications infrastructure a modern economy needs, not just in those places where the economy already works but right across the whole country,” Corbyn will say.