Alastair Campbell urges people outside Labour to sign up and vote against Jeremy Corbyn

The New Labour spin doctor said Mr Corbyn has to be stopped

Alastair Campbell (Getty)

People who are not members of the Labour party should register to vote in its leadership election so they can stop Jeremy Corbyn winning, Tony Blair’s former spin doctor has said.

Alastair Campbell, who served as New Labour’s director of communications from 1997 until 2003, claimed Mr Corbyn could destroy Labour if he became leader and said he had to be beaten.

“The madness of flirting with the idea of Corbyn as leader has to stop,” he wrote in a post on his blog. “That means no first preferences, no second preferences, no any preferences. It frankly means ABC, Anyone But Corbyn.

“Anyone who wants to see another Labour government one day should do what people who want a Corbyn leadership are doing – namely sign up as registered supporters for three quid in the next few days; but then I would hope they vote ABC.”

British Prime Minister Tony Blair, center, watched by his director of Communications and Strategy, Alastair Campbell, left (AP)

Mr Campbell is most notorious for his role in the preparation of the 2003 Iraq Dossier or so-called “dodgy dossier” that made the argument for Britain to invade Iraq.

Some Labour figures have previously criticised people signing up to vote in the contest and characterised them as “infiltrators”.

Mr Campbell also claimed that Mr Corbyn’s popularity was responsible for people rejecting the other candidates.

“One of the worst aspects of the so-called Corbynmania is that it is obscuring the solid decent abilities of the other candidates, who are each one of them better than most of the media will acknowledge, and far better equipped for the hard graft of detailed policy-making that has a chance of actually happening, so that we can make [change],” he argued.

A series of indicators including polls, local party nominations, and meeting attendance suggest that the left-winger is the favourite to succeed Ed Miliband to lead his party.

Mr Campbell is the latest New Labour figure to come out against Mr Corbyn.

Last month Tony Blair described the politics of the left-winger's supporters as "reactionary" and said anyone who believed in Mr Corbyn in their heart should "get a heart transplant".

Mr Corbyn is one of four candidates for the Labour leadership election – the others are Andy Burnham, Liz Kendall, and Yvette Cooper.