THE leaders of Scotland’s main pro-independence parties have publicly disagreed over what currency the country should use after leaving the UK.

Nicola Sturgeon and Patrick Harvie set out markedly different plans in the final TV leaders’ debate of the election campaign.

The SNP leader took a cautious approach with no fixed timetable, while the Scottish Greens co-leader said work on a new currency should start “immediately” after Scotland voted to end the Union.

Their Unionist opponents said it showed how the next parliament could be consumed by arguments within the Yes movement if a pro-independence majority was elected on Thursday.

Also in the BBC Scotland debate, Ms Sturgeon emphatically rejected the Tory claim that she would hold an illegal, wildcat referendum on independence if Boris Johnson blocked a legal one.

READ MORE: Nicola Sturgeon refutes Tory claims she is planning 'wildcat' referendum

Host Glenn Campbell came in for criticism from some leaders after asking about a proposed £200m Royal Yacht, which was roundly condemned as a “ludicrous" idea and a "stunt" by Mr Johnson to distract from rows over sleaze.

On the currency issue, the First Minister said an independent Scotland would continue to use the pound “for as long as necessary”.

She said the SNP's agreed policy was only to adopt a new Scottish currency “when the economic conditions, the fiscal conditions, the issues around trading and stability, were right to do that.”

Asked how long the process would take, Ms Sturgeon said it was “not absolutely fixed” and an SNP Government “would have to judge that” based on various tests.

However Mr Harvie, whose fellow co-leader recently said keeping the pound would be “catastrophic”, said: “For Greens, the purpose of independence is giving Scotland the ability to make the big economic choices about how we're going to invest in the future, about how we're going to take a different economic course than the unfair, unequal broken economy that came before Covid that's been managed by the UK Government. 

“And without an independent currency, I think you lack the ability to make those really big choices.”

Asked how soon he would move to a new Scottish currency, Mr Harvie said: “We believe that laying the groundwork for that should be part of the transition process.

"If Scotland votes for independence we should start laying that groundwork immediately.”

Asked what was wrong with the Greens' idea, Ms Sturgeon said: “We have to do it when the time is right.

"We have to debate these things when we’re asking people to make the choice of independence.” 

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Scottish Tory leader Douglas Ross accused her of being unable to answer a basic question and said an SNP majority would mean “this will be the debate we have in Scotland not the debate on recovery and rebuilding”.

Scottish Liberal Democrat leader Willie Rennie: “We have had a variety of different views from members of Nicola’s party and Alex Salmond and others including the Greens about what the currency should be.

“It just shows the deep-seated argument we will have for the next five years, because there is no consensus, despite the fact that it has been the policy of the SNP for generations, they still don’t know what the currency would be."

Ms Sturgeon also accused Mr Ross of "smears" and "untruths" about a wildcat Indyref2.

She added: "I have said consistently all along, sometimes to criticism from people on my own side of the argument, that I would not countenance an illegal referendum, not least because it would not deliver independence. 

"And I want Scotland, in the fullness of time, in due course, to become an independent country. 

"And I will be responsible about that, and I will build and ultimately, I think, win the case for independence through patient persuasion of people across the country."

Scottish labour leader Anas Sarwar said: “The problem with Douglas Ross’s approach is that he is a gift to the SNP and if he leads the opposition after this election he will be the gift that keeps on giving.”

Asked about the Royal Yacht, Mr Harvie called it an "absurdity", while Mr Rennie complained: "To be honest, I don't know why we're debating this. The royal yacht is a ludicrous idea. 

"It will never happen. It's one of Boris Johnson's tricks to try and attract attention. We should be focusing on things that make a difference to people's lives in Scotland."

Mr Ross said he understood private investment could be used to build the vessel. 

Asked if public money should be used on the project, he said: "Absolutely not".

The First Minister said: "The only reason Boris Johnson has been talking about this is to distract attention from the sleaze that is swirling around him and his Government - everyone should see through it."

Mr Sarwar described the move as a "cheap stunt".

After Mr Ross said his party wanted to reduce Scottish income tax levels to parity with the rest of the UK, Mr Sarwar accused him of wanting to give himself a tax cut.

Taking a dig at Mr Ross’s plan to carry on as the MP for Moray when an MSP, as well as his part-time work as a football referee, Mr Sarwar said: “You want go give yourself a tax cut for perhaps all three salaries you want to earn across Scotland.”

Alex Salmond’s Alba Party projected its name on BBC Scotland’s Pacific Quay building in Glasgow on Monday to protest at its exclusion from the debate.

READ MORE: Salmond: No 'exact number' for what constitutes independence supermajority

Mr Salmond yesterday accused the BBC of failing in its public duty.

Mr Salmond said his own show on the Kremlin-backed TV channel RT was "more balanced than the political discussion shows I've seen in this election on BBC Scotland". 

He said: "As an organisation, the BBC are guilty of a calamitous failure in terms of their obligations as a public service broadcaster."

He said BBC Scotland's "failure" in this area is going to be "a blot on their reputation as a broadcaster for years to come".