UNITE is under renewed pressure over an alleged secret plan to take control of Labour after a leaked minute confirmed the trade union is considering closer links with the far-left Momentum group.

Len McCluskey, the general secretary of Unite, said this week that there was “no proposal” for his trade union to support Momentum.

However, a minute of Unite’s governing executive council from last year stated: “He agreed that the Union should review the possibilities of more close working with this organisation.”

Corbyn’s leadership of Labour continues to divide opinion in his party and many of his MPs believe the left-winger has little chance of winning a general election.

A key section of his support base is Unite - Labour's largest affiliated union and donor - as well as the Momentum group formed during the contest that secured Corbyn the leadership in 2015.

McCluskey is currently facing a challenge for the general secretary post from moderate Gerard Coyne in a battle widely seen as a proxy for future control of Labour.

At the weekend, a newspaper revealed a secret recording in which Jon Lansman, the founder of Momentum, discussed plans for an official tie-up between the two organisations.

He said: “Assuming that Len McCluskey wins the general secretaryship, which I think he will, Unite will affiliate to Momentum and will fully participate in Momentum....”

The claim raised fears of two separate bodies joining forces in a bid to control the party.

Speaking to Sky News, Deputy Labour leader Tom Watson, who has clashed with Corbyn and McCluskey, said of the Lansman comments:

"It looks like a secret plan to take over the Labour party to me, and I think it needs to be called out.”

He also said: "I regard this as a battle for the future existence of the Labour Party. This is high stakes."

A furious McCluskey hit back at Watson: “There is another world in our movement, alas. A world of skulduggery, smears and secret plots. That is where you will find Tom Watson.”

“Anyway, backing groups like Momentum is not my decision to take, as Watson will know. Only Unite’s Executive could decide to support such an organisation, and there is no proposal that it should do so.

A Unite spokesperson said at the time that affiliation to Momentum was a "matter for our executive council alone and no discussion on the matter is scheduled".

However, the Herald can reveal that a meeting of Unite’s executive council in September discussed links with Momentum.

A minute of the gathering, which took place days before Corbyn was re-elected as leader, stated: “The General Secretary elaborated on the Union’s political work, in particular concerning the issue of the Labour Leadership. In response to a question from a member of the Council regarding Momentum, he agreed that the Union should review the possibilities of more closer working with this organisation.”

Lord Foulkes, a Labour peer, said he was in “no doubt” Momentum and Unite are planning on working together, adding: “This is a cause for concern. They are wanting to get control of the party and its assets and institutions.”

A Unite spokesman said: “Unite’s executive, not the general secretary, decides with which organisations the union works. This is clearly not the same as affiliation and should not be represented as such. There are no plans to affiliate to Momentum.”