Jeremy Corbyn's leadership has been plunged into crisis as a string of shadow ministers quit Labour's top team saying they had no confidence in his ability to win a general election.

As the fall-out from the EU referendum vote continued to engulf the party, eight members of the shadow cabinet announced they were walking out - with more expected to fallow.

Allies of the Labour leader insisted he had no intention of quitting - angrily accusing the rebels of plotting for months to get rid of him.

A series of senior trade unionists on Labour's ruling national executive committee rallied in support of Mr Corbyn - including Unite leader Len McCluskey and Dave Ward of the Communication Workers Union.

However the rebels warned he would be unable to form a new shadow team - with Labour MPs unwilling to serve under his leadership - if he tries to carry on.

The row erupted on another day of turmoil as:

:: Scottish First Minister Nicola Sturgeon warned the Holyrood Parliament could block the UK's withdrawal from the EU;

:: Former defence secretary Liam Fox became the first Tory to declare he was considering a run to succeed David Cameron.

The revolt of the shadow cabinet was triggered by the overnight sacking of shadow foreign secretary Hilary Benn following reports that he was orchestrating moves to mount a coup against Mr Corbyn.

First to go was shadow health secretary Heidi Alexander followed by the shadow minister Gloria De Piero.

They were followed by shadow education secretary Lucy Powell, shadow environment secretary Kerry McCarthy, shadow transport secretary Lilian Greenwood, shadow Scottish secretary Ian Murray, shadow Northern Ireland secretary Vernon Coaker and shadow Treasury chief secretary Seema Malhotra.

Shadow Commons leader Chris Bryant and shadow justice secretary Lord Falconer were reportedly also ready to quit.

In her resignation letter, Ms Powell said the party was facing an "existential threat" and she had no confidence Mr Corbyn's ability to lead them to victory if the Tories were to call a snap general election later this year in the wake of the Leave vote in the referendum.

"The task in front of us is immense. We have, over many years, lost the support of our traditional communities," she wrote.

"While I don't blame you personally for that, I do not believe you understand their concerns sufficiently to re-engage with these communities."

Mr Benn told BBC One's The Andrew Marr Show: "He (Mr Corbyn) is a good and decent man but he is not a leader and that is the problem."

Shadow chancellor John McDonnell - one of Mr Corbyn's closest allies - insisted that he had no intention of quitting.

In a thinly veiled warning to rebels, he said that Mr Corbyn still had the backing of the grassroots activists who swept him to the leadership last year and who will decide the outcome of any new contest.

"When people go back to their constituencies, the message will be straightforward - be loyal to the principles of the Labour Party," he told BBC Radio 5 Live's Pienaar's Politics. "Support the leader we elected nine months ago. Full stop. Accept the mandate."

However Mr Corbyn now faces as vote of no confidence which will be discussed at the weekly meeting of the Parliamentary Labour Party at Westminster on Monday with a secret ballot of MPs expected the following day.

Although the vote has no formal status, rebels hope that a defeat for Mr Corbyn will make his position untenable.

In a letter to Labour MPs, veteran backbencher Dame Margaret Hodge who tabled the motion warned the party was facing a disaster at the polls if they failed to act.

"If a general election is called later this year, which is a very real prospect, we believe that under Jeremy's leadership we could be looking at political oblivion."

Shadow international development secretary Diane Abbott - another of Mr Corbyn's allies - angrily turned on the rebels, accusing them plotting their move for months.

"The truth about today's coup attempt is that it has been long-planned," she told BBC News.

"Ordinary party members will not understand why Labour MPs want to set themselves at odds with the membership and, at this very difficult time, choose to play what are essentially Westminster games."