Nicola Sturgeon has been accused of trying to "duck away" from the hard questions about independence after one of her election candidates argued a customs border with England would help a separate Scotland create jobs.
The First Minister claimed not to have "directly" heard the comments by Emma Harper, who was a South Scotland MSP in the last parliament, despite the widespread ridicule and criticism they had received.
She also claimed that it was Brexit, not independence that would create a hard border even though the UK has already left the EU and there are no trade barriers between England and Scotland.
Ms Sturgeon insisted she did not want a hard border with England but experts say that would be the consequence of her plan for Scotland to leave the UK and join the EU. Scotland's trade with the rest of the UK is worth more than three times that with the bloc.
The row intensified the day after Ms Harper, the SNP's candidate for Galloway and West Dumfries, told ITV Border that "we can show that a border can work" if Scotland left the UK.
Although she said she wanted the "softest" of hard borders, she added: "There are issues that have been brought to my attention that show that jobs can be created if a border is created."
Douglas Ross, the Scottish Tory leader, said Ms Harper's comments were "incredible" for someone who represents an area on the English border and who serves as a parliamentary secretary to the SNP's tourism minister.
Arguing they "shed a light on the SNP's thinking", he said: "It’s always about independence, separating from the rest of the United Kingdom.
"But to somehow claim that they are benefits of our border between Scotland and the rest of the UK are completely false and fanciful."
Mocking Ms Sturgeon's claim not to have heard the comments, he said: "I think she’s probably the only person within Scottish politics that hadn’t seen that clip last night.
"Again, it shows that when it comes to more challenging questions Nicola Sturgeon tries to duck away from them rather than stand up and respond."
The First Minister told ITV: "I've not seen Emma's comments directly, but no one in the SNP wants a border between Scotland and England.
"This is only being talked about because the UK Government decided to leave the EU and rip Scotland out of the EU. I want Scotland to trade freely across the UK, and trade freely across the world's biggest single market – which is the EU."
The London School of Economics has estimated that independence would be between two and three times as costly as Brexit, even if Scotland joined the EU.