Sturgeon: Scotland needs same EU deal as Northern Ireland
It follows a report which claimed Northern Ireland will stay in the single market.
Scotland must get the same Brexit deal as Northern Ireland, the First Minister has said.
Nicola Sturgeon made the comments on Twitter after a report in The Guardian said EU negotiators would demand Northern Ireland be kept in the European single market and customs union to prevent a "hard border" with Ireland.
They are preparing to hand over an EU draft withdrawal agreement to British negotiators which the report said would contain "uncompromising legal language" concerning Northern Ireland.
It is designed to protect the economy between the north and south as well as the Good Friday agreement, with fears that border checkpoints could stoke old tensions and become paramilitary targets.
UK officials have reportedly been told that there could be a "sunset clause" in the legal text which means the arrangement could be nullified in the event of another solution being found in the future.
Examples of such hypothetical solutions include an "unexpectedly generous free trade deal" or an unforeseen technological solution to the border issue.
Speaking at a press conference in Brussels on Friday, the EU's lead Brexit negotiator Michel Barnier said the UK as a whole leaving the single market and customs union would make Irish border checks "unavoidable".
Sturgeon said single market membership for Northern Ireland but not for Scotland would put the country "at a massive relative disadvantage" economically.
The First Minister tweeted: "If NI stays in single market, the case for Scotland also doing so is not just an academic 'us too' argument - it becomes a practical necessity.
"Otherwise we will be at a massive relative disadvantage when it comes to attracting jobs and investment."
It marks a ratcheting-up of the First Minister's rhetoric on the issue, after previously saying there was "surely no good practical reason" why Scotland could not stay in the single market if Northern Ireland did.
Her remarks follow the leak of the UK Government's regional analysis of the impact of Brexit, which found that leaving the EU without maintaining single market membership would hit Scottish economic growth by 6% and Northern Ireland's by 8%.
A no-deal scenario would result in a 8% cut to growth in Scotland and 12% in Northern Ireland, the research indicated.
But Democratic Unionist Party (DUP) leader Arlene Foster, whose party backed Brexit, has previously said her party would not accept any regulatory divergence for Northern Ireland compared to other parts of the UK.
The issue previously came to a head in December last year when May had to pull out of a deal with the EU at the eleventh hour which contained compromises on the Irish border in the face of DUP resistance.
Theresa May's government relies on the support of DUP MPs to pass its budgets and survive confidence motions.
A deal which protected Northern Ireland's single market membership but not the rest of the UK's could topple May's government.
The UK and the EU are now in the second phase of Brexit talks around talk after an agreement was struck on the so-called £39bn "divorce bill" and the rights of EU nationals late last year.