Jeremy Corbyn has been publicly accused of undermining Labour's efforts in the European Union referendum campaign as his grip on the party leadership looked increasingly weak.
Former home secretary Alan Johnson, who ran Labour's campaign for a Remain vote in the referendum, claimed the leader's office had "conflicting objectives" to the rest of the party.
His comments came after another wave of shadow cabinet ministers quit in protest at his leadership and it appeared inevitable he would face a challenge to his position.
Luciana Berger quit her shadow cabinet-level role as mental health minister saying "loyalty to the party must come first", becoming the eighth member of Corbyn's top team to resign on Monday, after 12 resignations on Sunday.
The full-blown coup aimed at ousting Corbyn follows the dramatic events in the wake of the Brexit vote, with Labour MPs fearing an early election against David Cameron's successor.
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Despite Corbyn's insistence that he was firmly behind the Remain cause, he has a history of Euroscepticism and the party's MPs have publicly questioned his commitment on the issue.
In an email to colleagues as Parliament returned following the vote for Brexit, Johnson wrote: "Everyone else needs to make their own assessment as to whether more could have been done to prevent this disastrous result. I will certainly do this, as I hope will the leader's office.
"At times it felt as if they were working against the rest of the party and had conflicting objectives.
"I was proud to work with some great people who tried their very best to get the result we all wanted. Nobody in the leadership had the right to undermine their efforts."
