A SECOND independence referendum will surge on to the agenda if Britain plunges to a disastrous “no-deal” Brexit, according to Scotland’s leading EU expert.

Kirsty Hughes, director of the Scottish Centre on European Relations (SCER), believes First Minister Nicola Sturgeon would be forced to rekindle her own exit plan as the UK “descends into ever more chaos”.

Her remarks in a new paper by her organisation came as opposition MPs criticised the UK Government for refusing to reveal any research on the impact of Brexit on Scotland.

Earlier this year, James Chapman, a former aide to David Davis, the Brexit Secretary, claimed the department had undertaken such analysis, which showed Scotland and the north-east of England would be worst hit by leaving the EU.

In response to a subsequent Freedom of Information request, the department yesterday said it would neither confirm nor deny it had undertaken such analysis because to do so could undermine the Brussels talks and provoke a “reactionary” response from stakeholders north of the Border, which could damage Britain’s economy.

Christine Jardine for the Liberal Democrats said the response was “both idiotic and offensive”, while the SNP’s Peter Grant said “Whitehall gobbledegook” suggested ministers were “desperately trying to conceal” the damage Brexit will cause Scottish jobs and living standards.

A succession of experts has warned a “no-deal” Brexit would bring crippling tariffs on exports, huge price hikes for food, drugs shortages and an immediate cancellation of thousands of flights.

Dr Hughes said such a scenario, sometimes called “the cliff” because of its predicted economic effects, could also spark a new UK constitutional crisis and another general election.

She wrote: “If the UK Government either falls or the Brexit process descends into ever more chaos, a second independence referendum may come back on the agenda sooner than some expect.

“With a hard Brexit or ‘no-deal’ Brexit most likely under the current UK Government, those on the pro-independence side who want to disentangle the arguments for independence from Brexit may find that is not possible in the coming crucial and uncertain year.”

However, Dr Hughes added that a retreat from a likely no-deal or hard Brexit could offer the Unionists a reprieve.

She wrote: “A soft Brexit or no Brexit would undermine any case for an urgent second independence referendum.”

Dr Hughes, a veteran of London and Brussels think tanks, has set out four scenarios for the next 18 months: no-deal; a hard Brexit, with a Canada-style trade deal; a damage-limiting soft Brexit and no Brexit.

Her paper looks in detail at how British and Scottish parties would respond to “the political and economic turmoil of a ‘no deal’.

She said it would be unlikely that Northern Ireland’s DUP - currently propping up Prime Minister Theresa May’s minority administration - would stick by the Tories meaning a general election at the end of 2018 or beginning of 2019.

Dr Hughes wrote: “In Scotland, the SNP would quite likely benefit if the Tories and Labour (including in Scotland) were both still supporting Brexit at this point.

“One possible outcome for a crisis election would be that the LibDems, along with the SNP, could end up holding the balance of power.

“The SNP would face a choice of whether to go for a second independence referendum as Brexit chaos and damage mounted in this scenario.

“How public opinion shifts in Scotland in a ‘no deal’ scenario would be centre stage. The absence of a ‘Brexit bounce’ towards independence since June 2016 could persist – though a ‘no deal’ outcome would certainly test that.

“And the SNP will still have to contend with the third or so of its supporters who have until now backed ‘leave’.

“But even if public opinion shifted towards independence, the general election would happen first – except in the unlikely case that the DUP were still propping up the Tory government as ‘no deal’ unfolded.

“If the Tory government lost a vote of confidence at Westminster, a new UK government would need to agree to a second independence referendum after the general election.

“So, in an election context, the SNP would have to decide whether, with the LibDems, to make a second EU referendum a condition of support for a minority Labour government (if that happened) or whether they might instead ask for support for a second independence referendum – or both.”

That decision, stresses Dr Hughes, would not be easy.