NICOLA Sturgeon has suggested a special deal for Northern Ireland that effectively kept it in the European single market would be a “big worry” as it would put Scotland at an economic disadvantage.

The First Minister argued that in such circumstances Scotland should remain effectively in the single market too and that any backstop deal should equally apply to Scotland, declaring: “I don’t want[border] checks.”

She told Sky News: “If we are looking down the road to a situation where Belfast is still in the single market, and Glasgow is not, then any responsible First Minister of Scotland is going to say: 'That's a big worry for us.'

"So, it just underlines this notion that however it happens over the next few years, whether it's through a differential relationship with Scotland with the EU, or whether it's around Scotland looking again at becoming independent and securing its relationship with the single market that way, it will become very important for us to find a way of doing it."

But Scottish Conservative MP Stephen Kerr said: “Nicola Sturgeon knows that having a separate backstop for Scotland would mean having regulatory and custom checks at the border with England.

“Nearly two thirds of Scotland’s trade is with the rest of the United Kingdom, putting up barriers to this will only hinder the flow of goods within the UK and add layers of unnecessary bureaucracy. It is unacceptable for businesses and will damage the integrity of the UK’s internal market.”

The Stirling MP added: “Nicola isn’t about getting a good Brexit deal for Scotland. Nicola and the SNP are all about disrupting and frustrating the Brexit process purely to help further their obsessive pursuit of independence. The conference this week is clearly showing that.”

Earlier, the FM was slapped down by Theresa May, who urged the FM to “respect” the result of the 2104 independence referendum, making clear she would not facilitate another vote on Scotland’s future in this parliament.

The PM's rebuttal came after Ms Sturgeon had earlier insisted it would be “absurd” and “anti-democratic” for Mrs May to refuse to facilitate a second vote on Scotland's future and that such a position could not be sustained.

When it was pointed out, as in 2014, the Scottish Government would require a legal settlement with the UK Government - which, through Westminster, has the power over constitutional matters, such as holding referendums – and that the PM had made clear she would not agree to one, the SNP leader said: “I find this argument…is just accepted is really absurd. What we have here is: I am First Minister of a government elected on a clear mandate for a referendum in these circumstances.

“Theresa May, the Tories, Labour, they are absolutely entitled to oppose Scottish independence; that’s their democratic right but to argue that they should go beyond that and stand in the way of people in Scotland having the right to choose is a deeply anti-democratic argument and I don’t think it’s one over the medium to long term that can hold,” she added.

In response the PM's spokesman said: "We've made our position on this repeatedly clear. Scotland already had an independence referendum just four years ago and voted decisively to remain in the UK.

"This should be respected. As the Prime Minister has said, now is not the time for a second independence referendum, now is the time for the United Kingdom to be pulling together to get the right deal for the United Kingdom and the right deal for Scotland in our negotiations," he added.