Len McCluskey today warned Labour’s governing body against a “sordid fix” that could mean Jeremy Corbyn struggles to make the ballot paper in the upcoming leadership election.

The party’s NEC will meet today to draw up the rules around the contest, including whether Corbyn will be required to secure the nominations of 20 per cent of Labour MPs and MEPs. But the Unite General Secretary said this morning that the rules are “very clear” and that it would be “alien to the traditions of the Labour Party” if Corbyn is not automatically on the ballot.

The ruling committee will meet at 2pm today – see what they are set to discuss here.

McCluskey was speaking on the Today Programme from Unite’s policy conference in Brighton, where he yesterday gave a fiery address to delegates about the upcoming Labour leadership contest. He stood by his comments today, telling the BBC that the attempt to remove Corbyn has been “a political lynching and it was squalid.” He also attacked the “histrionics of resignations” from the Labour frontbench over the last fortnight, and said that Angela Eagle had not needed to wait weeks to put her challenge to Corbyn.

He stopped short of saying that Unite would back legal action if the NEC rule that Corbyn requires the nominations – as the leader himself hinted at over the weekend. But he said that it “would be seen as a sordid fix, and I think it would be alien to the traditions of the Labour Party and alien to the concept of natural justice that Jeremy Corbyn is not automatically on the ballot paper.”

The trade union chief said that he hoped everyone in the party would accept the result of the election, but that people would not accept a process they saw as unfair.

“We should try and conduct the campaign in a civilised manner, and I will accept the results, I hope everybody else will, but I won’t accept a fix,” he said.

“I accept the democratic processes of the Labour Party. Let Jeremy go on the paper, let him be involved in the arena of political debate, and let our members in the Labour Party decide who they want as our leader. I will accept that democratic role.”

McCluskey denied that there could be different interpretations to the rules. “The rules are not ambiguous on this,” he said, adding that “it says very clearly where there is no vacancy” it is the challenger who requires nominations.

A legal opinion prepared for Unite and seen by LabourList indicates the sitting party leader does not need to find a fresh round of nominations to stand in any contest.

“The rules by which the Labour Party is governed are unambiguous: the leader does not require any signatures to be nominated in a leadership election where there is a potential challenger to the leadership,” it states.

McCluskey also dismissed Election Data/YouGov polling that came out last night, which appears to indicate Unite members losing faith in Corbyn’s leadership. “These kinds of polls can be twisted and interpreted in many different ways,” he said.

Update 10am: Unite the Union has published a statement on the Labour leadership which echoes McCluskey’s comments this morning.

The union believes the contest “is an unhelpful process to be embarking upon at this time” but urges “all sections of the party to act with dignity and respect”.

On whether Corbyn should be on the ballot automatically, the statement says: “the only way for any challenger to Jeremy Corbyn to seek a legitimate mandate from members to lead our party is through a fair and open election in which the elected leader is able to defend himself, his record and his programme.

“To do anything else would leave a stain on party unity that might prove permanent.

“While it is only right that we all accept the result of a fair election whatever it is, for our party’s safe and stable future, we must never accept a fix.”