A FURIOUS row has erupted in Scottish politics after Labour leader Richard Leonard said Jeremy Corbyn must “get a move on” with plans for a federal British state.

In an exclusive interview with the Sunday Herald, Leonard said he wanted Labour to set out a radical alternative to Scottish independence. His comments immediately sparked a row with pro-independence and unionist parties bitterly clashing over the call for a major reshaping of the British state.

The SNP and Greens savaged Leonard for his intervention. However, it was welcomed by the Liberal Democrats - the only party to fully embrace the policy of federalism.

Labour and Tory supporters of a federal UK gave a cautious welcome to Leonard's call for what would be one of the most radical shake-ups of the UK's constitution.

The big read: Can federalism ever work in the UK?

Federalism could see parliaments in the four nations of the UK - Northern Ireland, Wales, Scotland and England - sharing equal powers, with a federal government retaining control over foreign affairs, defence, currency, welfare and pensions. There are concerns, though, that England could dominant any federal system. Other forms of federalism envision the creation of regional assemblies across England to prevent a single English parliament overshadowing Belfast, Cardiff and Edinburgh.

Leonard has been largely silent on the constitution since his election last November. However, in an exclusive interview with the Sunday Herald, Leonard called for radical changes to Westminster's relationship with the devolved nations.

Leonard said he would be “pushing” for Corbyn to commit to legislate for a federal UK if Labour wins the next General Election. He added: "I'm in favour of abolition of the House of Lords and I can see there being a case (for federalism), especially if we are moving towards a more federal constitution with a second chamber that is comprised of representatives from Scotland, Wales and the regions of England and Northern Ireland. So I can see that there is a strong case that kind of reform."

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Corbyn's shadow cabinet office minister Jon Trickett was asked to examine plans for federalism in early 2017. However, Trickett's "constitutional convention" has yet to state its position.

However, Leonard said that if the Westminster parliament ran its full term until 2022, that an incoming Labour government must be poised to legislate for a federal UK.

Leonard said: "Labour under Jon Trickett’s stewardship has been talking about establishing a constitutional convention that would consider those kind of matters. If there's a quick election this year, which there might be, that's not going to come to the end of its work. But if there was to be another four years before the general election, by then I would hope that Labour would have firm plans for those kinds of constitutional reform. Certainly I'm pushing for the UK Labour Party to get a move on with its constitutional convention."

The Sunday Herald approached Trickett for a response to Leonard's remarks about federalism. Last night, Trickett could not be reached.

However, the SNP claimed Labour at Westminster could not be trusted to legislate for a federal UK. SNP MSP George Adam said: “The fact is that Labour has been promising federalism and the end of the Lords since the dawn of time and have never delivered – billions of years from now Labour politicians will no doubt be staring into the dying sun still calling for a reformed federal Lords. If they had a shred of integrity on this issue they’d join the SNP in refusing peerages.”

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Patrick Harvie, the co-convenor of the pro-independence Scottish Greens, said there was no interest in the idea of a federal UK south of the Border. Harvie said Leonard's plan failed to address Westminster's Brexit "power grab, that he claimed would see London take charge of policy areas traditionally devolved to the Scottish Parliament, when the powers are repatriated from Brussels".

Harvie said: "There is zero appetite for federalism in the English regions. We've seen the contempt that the UK Government has for Scotland, Wales and Northern Ireland with its Brexit power grab and above all we need to challenge that. Richard Leonard's comments are a step in the right direction, but he needs to recognise that the UK government's behaviour towards the devolved nations is something we need to stand up against."

However, Leonard's shift was welcomed by former Labour First Minister Henry McLeish - a longstanding advocate of federalism.

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McLeish said: "The main issue is to create a debate about federalism for the UK and the benefit that would bring to Scotland. It seems to me that after many centuries the British Parliament needs to be radically altered. I sincerely hope that the Labour leader in Scotland will push as hard as possible to make this happen at UK level."

Senior Tory MSP Murdo Fraser, who supports federalism, also welcomed Leonard's remarks. However, Fraser, Scotland's shadow finance secretary, challenged Leonard to set out detailed proposals for a new devolution settlement.

The big read: Can federalism ever work in the UK?

Fraser said: "In the past we have seen Labour figures like Gordon Brown propose federalism as a desirable option for the UK, but without any detail on how we would see such a system work. Richard Leonard is going further than his predecessors, but there are a huge number of questions as to how the system would work in practice."

Scottish Lib Dem leader Willie Rennie said there was growing cross party support for a federal UK as an alternative to independence. Rennie said: “Support for federalism has been part of the DNA of the Scottish Liberal Democrats for a very long time. I’m glad that Richard Leonard is speaking out in support of common sense steps to promote joint action.”