NICOLA Sturgeon has promised a detailed explanation of how customs checks with England would work under independence after being challenged about possible smuggling. 

The First Minister pledged a future paper in her prospectus for leaving the UK would set out more information, including what technology could be used to minimise disruption to trade.

She admitted the Scottish Government was still “in the process” of scoping out possible systems.

It came after the latest part of the Building a New Scotland series said physical checks were likely on just the two main trunk routes between England and Scotland, the A74(M)/M6 at Gretna and A1 at Berwick-upon-Tweed, and at rail freight terminals. 

That would leave around two dozen road crossings across the 154 kilometre border unchecked, including the A7 through Hawick, the A68 through Jedburgh and the A697 through Coldstream. 

Under Ms Sturgeon’s plan, an independent Scotland would rejoin the EU, meaning the border with post-Brexit England would become a tightly regulated external EU border.

At last week’s SNP conference, Professor Nicola McEwen, co-director of the Centre on Constitutional Change, said that would mean at-border checks, calling it a “technological and physical challenge” but not an insurmountable one.

She said: “On the other hand, it's an awful lot of traffic to go through not very many crossing points. So there would inevitably be pressures on trade crossing that border.” 

Today’s prospectus paper said an independent Scotland could “draw on best practice from around the world” as it sought to agree a border regime with the EU and rest of the UK, ideally with the UK and Scottish authorities making checks on each other’s behalf.

Asked about the potential for smuggling across the border if just two customs checks were used, Ms Sturgeon said: “We will publish further details around European Union issues.

"So some of these issues we will develop further from what is in this paper. 

“We are being candid here about the implications of Scotland being back in the EU and the rest of the UK - wrongly in my view - being out. 

“We would, as many other countries already do, increasingly use technology to do this.

“Are these challenges that we wish we didn't have? Yes, but if we want to be back in the EU with the many benefits that come from that, we have to overcome these challenges.

“It is possible to do, in my view, with proper planning.”

Pressed on whether there would be border checks on the England-Scotland border, Ms Sturgeon said: “There will have to be arrangements in place for the transport of goods.

“But let’s not lose sight of two things.

“Firstly, with proper planning, the ability to do that in a way that doesn't disrupt trade.

“Trade between Scotland and England is important, trade between England and Scotland is important to England. But that should not be the limit of our ambitions. 

“We have a market seven times the size of the UK on our doorstep and we should be seeking to create arrangements in place that allow trade across that.

“These arrangements can be done in a way that doesn't disrupt trade, but the benefits we get from that, I think outweigh the challenges that will come from it.” 

Pressed on what technology exactly she had in mind for the border, the FM said: “We've set out the initial analysis of what will be required in this paper.

"We will supplement that in future papers.

She said the EU was looking at a “single trade window model”, while Norway and Sweden used technology, adding: “We are intent on setting out as much detail as we possibly can to inform these decisions. Ultimately it will be a decision for people in Scotland to weigh up and take. But the process we're going through right now is intended to fully inform it.”

Asked why there was “no detail” about the technology included in the paper, Ms Sturgeon said: “We’ve set out the broad approaches that other countries take, and we are in the process of looking at that international best practice as we design how this would work for Scotland, and that will be detail that we set out in more depth in a future paper in the series.”