SHADOW Chancellor John McDonnell says “a soft coup” has been launched against Jeremy Corbyn by “elements in the Labour Party”.

McDonnell accused unnamed “plotters” and the “Murdoch media empire” of a “co-ordinated and fully resourced” effort to oust Corbyn.

In an article for party magazine Labour Briefing, he said “the plotters” were using “an exceptionally well-resourced dark arts operation” to “destroy Jeremy Corbyn” and said they were so determined to get rid of him they were not only prepared to jeopardise their own seats, they were also ready to endanger the very existence of the party.

“We have to alert party members and supporters that the soft coup is under way,” he wrote. “It’s planned, co-ordinated and fully resourced. It is being perpetrated by an alliance between elements in the Labour Party and the Murdoch media empire, both intent on destroying Jeremy Corbyn and all that he stands for.”

McDonnell added, after last year’s failed coup attempt, the plotters realised a direct attack was liable to provoke a backlash from grassroots party members, so they were now working behind the scenes to destabilise Corbyn.

It is understood McDonnell wrote the article after Tony Blair attacked Corbyn over Brexit and before Labour’s Copeland by-election loss but it was only posted on the Labour Briefing website on Sunday night.

“As John said yesterday, he wants us all to focus on party unity following last week’s by-election results,” a source close to McDonnell added.

“And he is looking to reach out in the coming days to those across all sections of the party and none.”

Corbyn was the overwhelming winner of Labour’s leadership election in 2015, despite having the support of only a small number of MPs. A challenge to him last year led to another vote of all Labour Party members and affiliates, which he again won overwhelmingly.

But many of the party’s MPs have continued to be unhappy with his leadership, and the party trails the Tories in opinion polls.

On Sunday, Corbyn said Labour’s by-election loss showed “the scale of how hard our task is to persuade people of our message”.

In a speech to the Scottish Labour conference in Perth, he urged his party to “remain united” and not to “give up”.

Labour lost the seat of Copeland, in Cumbria, to the Conservatives last week - the first by-election gain by a governing party in 35 years. However, it managed to hold off a challenge from UKIP in a by-election, in Stoke-on-Trent Central, which also took place on Thursday.

Corbyn yesterday insisted he was “very happy” and Labour was moving forward. Welcoming Gareth Snell, the new MP for Stoke-on-Trent Central to Westminster, Corbyn said the victory showed the people of Stoke “rejecting the politics of fear and instead voting for the politics of hope”.

On McDonnell’s coup warning, he said: “I am very happy, we are going forward. Policies will be coming out, campaigns are going on.”