Nicola Sturgeon has said that she "does not accept" the rationale that the Natwest's group's balance sheet is too big for an independent Scotland.

Speaking after Alison Rose, chief executive of Royal Bank of Scotland owner NatWest Group, said that the bank would move its HQ to London in the event of Scottish independence, the First Minister said the plan was to engage "constructively" with businesses.

Ms Rose said on Thursday that the Edinburgh-based bank has “always been very clear” that its balance sheet would be “too big” for an independent Scotland, and that it would have to move.

READ MORE: Natwest Group boss — We would move HQ to London in event of Scottish independence

Royal Bank of Scotland is one of the country's biggest private sector employers and supporters of businesses and households.

Ms Sturgeon said that the issue had previously come up in 2014, when the bank said it would have to move its registered office to secure the protections remaining in the UK would bring.

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Confronted with the issue again on BBC Radio 4, Ms Sturgeon said:  "I don't necessariy accept all of that case, but I do acccept that we have to engage constructively with businesses of all shapes and sizes. 

"But Scotland, like countries of comparable size, is perfectly capable of being independent. We have a strong and vibrant business base in Scotland.

"But I do accept that we have to have those discussions."

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Ms Sturgeon said that the SNP's plan in the first days of independence was to continue to use Sterling and move to the country's own currency alongwith establishing a central bank.

She said: "We had this debate in the final stages of the referendum campaign in 2014, and banks at the time talked about registered offices, not operations, not jobs. 

"But at the heart of this debate is, for those who are against independence, this ridiculous notion that somehow, uniquely, among countries around the world, Scotland is incapable of being independent. 

"I don't accept that. Scotland would be a thriving, successful, independent country."

Ms Sturgeon conceded that an independent Scotland would need to confront border issues with the rest of the UK if returning to the European Union.

Concerns have been raised by critics of Scottish independence who say Scotland rejoining the EU would result in a hard border with England.

The First Minister told BBC Radio 4’s Today programme on Friday that the government of an independent Scotland would negotiate terms to “allow businesses to keep trading”.

Ms Sturgeon said: “This is the frankness that certain sections of the media will seek to stir up trouble on – I am not denying that we would need to confront and resolve the issues of being in the European Union for the border between Scotland and England.

“If we do that in a way that allows businesses to keep trading, because businesses are already paying the price of having a border because of Brexit, we open up the European Union again.

“That is massively important for Scottish businesses, and also makes Scotland more attractive again in terms of inward investment to secure that access to the single market.”

The First Minister also said Scotland would remain in the common travel area with the rest of the UK and Ireland, adding “nobody with any shred of credibility” is suggesting otherwise.