A ROW between the rival camps for the Scottish Labour Party leadership erupted last night amid fears of a trade union stitch-up to install the left-wing Corbyn-supporting candidate.

Richard Leonard, a prominent trade unionist, rejected outright suggestions that Len McCluskey’s Unite had put him on course for a decisive victory over his rival Anas Sarwar, seen as a moderate Centrist, saying such claims were “complete nonsense”.

Sources close to Mr Sarwar warned that Scottish Labour activists “wouldn’t take kindly” to any attempt by Unite to return the party to “a branch office”.

The warning came after reports that Unite had signed up 2,700 members to the union’s political levy – a payment that makes them eligible to vote in the leadership contest - in just two days last weekend.

The signing up of 2,700 members, who responded to a mass text and email campaign, comes in addition to the 5,000 levy-payers the union already has.

Also, it emerged that a majority of four on a panel set up to vet new Labour members, who join during the leadership contest, are on the Left of the party.

It is understood that moderates only account for three of the places on the seven-person body, which is chaired by interim leader Alex Rowley, known to be a key ally of Jeremy Corbyn.

A party source said the balance of the panel would make a purge of left-wing recruits “very unlikely”.

Mr Leonard, who will face his rival at a hustings at the Labour conference in Brighton later today, told The Herald that he did not believe that the surge of Unite members to pay the political levy would have a “distorting impact on the outcome of the election”.

“There are 21,000 members of the Labour Party and they will determine who the next leader of the Scottish Labour Party is and I’m quite happy to make my appeal to them and for them to be the judges of me on my policies, the consistency of my politics and the values I hold,” declared the Central Scotland MSP.

As well as getting the official backing of Unite in Scotland, Mr Leonard also has the support of three other major unions: Usdaw, TSSA and Aslef. Unison is due to meet today to decide who it will officially back and the expectation is it will be the 54-year-old left-winger.

Mr Leonard said he was grateful for the breadth of support he had received from parliamentarians, councillors, the grassroots and trade unions.

“The trade unions set the Labour Party up and trade union members are the very people that the Labour Party should be reaching out to and any trade union members who are considering becoming affiliated supporters should consider becoming full members of the Labour Party because that’s where they belong,” he explained.

Asked about fears of a union stitch-up, Mr Leonard replied: “It’s complete nonsense.”

He insisted that it was “absolutely not” the case that just because a union officially supported someone that its members would cast their vote the same way.

Asked if he won, then some believe Mr Corbyn would have his man leading Labour in Scotland, Mr Leonard replied: “That is not how I see it. My mandate would come from the members of the Scottish Labour Party not from anywhere else and it’s to them that I would be accountable.”

He added: “I’m not a Corbynista. I have been espousing these views for 35 years.”

However, the Sarwar camp appeared concerned about the prospect that the unions alone could ensure Mr Leonard wins the Labour crown.

One senior source close to the Glasgow MSP said: “Scottish Labour fought hard for its autonomy from the UK party. Members won’t take kindly to any attempt by Unite to return Scottish Labour to a branch office.”

This was a reference to the famous line used by Johann Lamont, who in October 2014 when she resigned as Scottish Labour leader, complained that there were some people in Westminster who regarded the Scottish party as a “branch office”.