JEREMY Corbyn has ruled out any form of alliance with Nicola Sturgeon’s SNP, saying the Nationalists would be unreliable allies "for a radical Labour government”.

As the party leader arrives in Scotland – having secured a seat on the London to Glasgow train – tension is mounting ahead of his head to head hustings with challenger Owen Smith tonight at the Scottish Exhibition and Conference Centre given the fractious exchanges of the last 48 hours.

The Welsh MP, in an interview with the New Statesman magazine, fired off another criticism at his colleague, claiming Mr Corbyn was more interested in being leader of the Labour Party rather than Prime Minister of the United Kingdom.

Stressing how he was “deeply worried” the MP for Islington would try to stay on as leader even if Labour lost the next general election under his leadership, Mr Smith said: “He’s determined to hang on come hell or high water. And what does that say about him?...

“He is actually prepared to sacrifice unity and victory – two great words that have traditionally been emblazoned on Labour banners through the ages – in order to secure control of the party,” the Pontypridd MP added.

Today, Mr Corbyn is due to given a speech on anti-austerity and also attend a pre-hustings rally at Glasgow's Crowne Plaza Hotel before his showdown with Mr Smith, who has received the support of Scottish Labour leader Kezia Dugdale.

Ahead of the hustings, both candidates pledged to invest £20 billion in Scotland if they were elected to lead a UK Labour government.

Earlier this month, Dave Anderson, the shadow Scottish secretary, urged Labour to consider an SNP coalition "if that is the price that we have to pay to prevent another rabid right-wing Tory government".

But The Herald revealed on Monday that Mr Corbyn had ruled out any deal with the SNP as Mr Smith has already done. Before the last election it took Ed Miliband weeks before he finally and categorically ruled out Ms Sturgeon’s offer of some kind of Labour-SNP alliance to keep the Tories out of power in a hung parliament.

In an article for the Daily Record, the Labour leader accused the SNP of pursuing Conservative-style policies such as a benefits cap and low corporation tax and of "relentlessly" attacking councils.

He recognised many Scottish Labour supporters who were hungry for change have shifted to the SNP but insisted these people were not being well served by the Nationalists.

"Just under a year ago I was elected leader of the Labour Party because people could see a need for change. That need for change isn't going away - and neither am I," declared Mr Corbyn.

He went on: "It's Labour's commitment to making that difference that means we're not looking for an alliance with the SNP.

"Let me make it clear. I will welcome support for all or any of our policies from any other political groups or parties...but I'm well aware that Labour and the SNP come from different traditions and have different goals.

"I don't see a party that welcomed George Osborne's corporation tax cuts, relentlessly attacked local government and is committed to a benefit cap as reliable allies for a radical Labour government.

"There are many people who have voted for, or even joined, the SNP who want to see many of the changes we want to implement. I don't think these people are always being served properly by the SNP."

Earlier this month in an interview with The Herald, Mr Smith categorically ruled out any "backroom deal" with the SNP should he become leader, stressing how the public hated them and how the Nationalists were "not a proper social democratic party".

Mr Corbyn said the SNP Government had pursued a low tax agenda while the NHS and councils struggled under austerity and Scotland lacked decent jobs and affordable housing.

He pledged to create a Scottish National Bank to deliver £20bn investment in projects and small businesses and backed Scottish Labour's plan for a publicly-owned railway and energy sector.

Tomorrow, the Labour leader will make further speeches in Edinburgh and Dundee.

Earlier, he was, following the political spat over train overcrowding dubbed traingate, able to secure a seat on the Euston to Glasgow train.

Twitter user David Rose posted an image of the Labour leader and said: "My kids just got on @VirginTrains from Euston to Glasgow with @jeremycorbyn. He has a seat. Good job @richardbranson."

Virgin Trains wished Mr Corbyn a "great trip" to Glasgow. In a Twitter message the operator said: "Welcome onboard! Hope you all have a great trip to Glasgow this morning."