Tom Watson urges Jeremy Corbyn to tackle 'Trotskyist entryism'
Tom Watson has hit back at claims he is peddling conspiracy theories about hard left plots to manipulate the Labour leadership contest.
Labour's deputy leader claims Marxist groups are attempting to use Momentum - Jeremy Corbyn's network of supporters - to "further their revolutionary aims".
He is urging Mr Corbyn to join him in tackling their "entryist" tactics.
Mr Corbyn's leadership campaign has dismissed Mr Watson's claims, first made in the Guardian.
A spokesman for the campaign said on Tuesday that he should be trying to "unite" the party rather than "patronising" its members with such talk.
'Not conspiracy theory'
But Mr Watson has stood by his claims - and has now written to Mr Corbyn urging him to take action against two groups he says are attempting to infiltrate the party.
"My comments in the Guardian were amplifying what we both know to be true; that there has been an increase in members of proscribed organisations attempting to join the party, in particular members of the Socialist Party (formerly Militant) and the Alliance for Workers Liberty (formerly Socialist organiser)," he writes.
He adds: "It's not a conspiracy theory to say that members of these organisations are joining Labour, it's a fact."
He goes on to challenge Mr Corbyn to take action against these groups, saying: "I assume that you still support the proscription of other political parties.
"If the position has changed, please just let me know because I think it would be useful to discuss this within the party."
He adds: "For the avoidance of doubt I am asking you to confirm that you believe members of the Socialist Party and the Alliance for Workers Liberty should not be allowed to be members of the Labour Party, given the proscription of these two groups by annual conference during Neil Kinnock's leadership."
Militant was expelled from Labour in the 1980s amid claims it was using Trotskyist entryism tactics to secretly take over the party and transform it into a revolutionary socialist movement.
Mr Watson has passed a document to Mr Corbyn he claims is being is shared by Momentum members with links to far left groups, setting out a a step-by-step guide to taking control of local Labour Party branches.
It includes a list of tactics described in a 1984 book on the rise of Militant by journalist Michael Crick, including making meetings boring to "turn-off" the "faint-hearted" and making party events "adversarial" with "uncomradely questions to sitting councillors and the MP".
"This behaviour basically reduces the attendance of the sensible types. Then the meeting (is) ours to control," it says.
Owen Smith, who is attempting to unseat Mr Corbyn in a leadership contest, refused to be drawn on Mr Watson's claims, telling BBC News he could "speak for himself," adding that he was pleased the party was now a "mass movement".
Former Shadow Attorney General Lord Falconer told BBC Radio 4's Today programme the "vast, vast majority" of new members have nothing to with far left entryism.
But he added: "I'm sure there are some individuals who are old Trots, old members of Militant who were expelled in the eighties, who are using the wholly new situation in Labour to come back."
What is a Trotskyist?
Trotskyism has its origins in early 20th Century Russian politics and the path pursued by one of the founders of the Soviet Union, Leon Trotsky.
Trotsky was the head of the Red Army and a key player in the violent revolution that toppled the Russian tsar and established the world's first socialist state.
But he split with the other revolutionary leaders Lenin and Stalin, who believed they could create a socialist society in their own country without a world revolution.
Trotsky believed his country could achieve socialism only if the working classes around the world rose up as one to overthrow the ruling classes - the doctrine of "international socialism".
In his Guardian interview, Mr Watson said he did not believe that the "vast majority" of Labour members that had joined the party recently were "all Trots and Bolsheviks".
But he added: "But there are some old hands twisting young arms in this (leadership) process, and I'm under no illusions about what's going on.
"They are caucusing and factionalising and putting pressure where they can, and that's how Trotsky entryists operate."
"Sooner or later", he added, "that always ends up in disaster. It always ends up destroying the institutions that are vulnerable, unless you deal with it."
Mr Watson said the "Trots" did not have the party's "best interests at heart", but saw it as a "vehicle for revolutionary socialism" and were "not remotely interested in winning elections".
A spokesperson for the Jeremy for Labour campaign, which is being led by shadow chancellor John McDonnell, said Mr Watson's remarks to the Guardian were "disappointing" and Labour members wanted a "politics of hope" rather than "Project Fear".
"Rather than patronising members and peddling baseless conspiracy theories about 'Trotsky entryists', he should be working with Jeremy to unite our party so that we can get back to campaigning to dislodge this Tory government, and help elect a Labour government in its place," the spokesperson added.