A THINK-tank has warned that if a fresh independence referendum were to be held in March 2019 there would still be “some substantial uncertainty” about the implications of the UK’s departure from the European Union – and about an independent Scotland’s future relationship with the EU.

The warning comes in the latest policy paper from the Scottish Centre on European Relations (SCER) as First Minister Nicola Sturgeon and Prime Minister Theresa May have reached a stalemate over the prospect of another indyref.

Sturgeon has insisted that holding a vote between autumn next year and spring 2019 would allow Scots to make an informed choice between Brexit and independence.

But May has made clear “now is not the time” for Scotland’s future in the UK to be put to the vote.

Dr Kirsty Hughes, an expert on European politics and founder of the SCER, said: “If there were a second independence referendum in March 2019, Scottish voters would know a lot more than now about the outcome of the Brexit talks, and about whether an independent Scotland would definitely aim to re-join the EU. It will not be a moment for fudging that choice.”

In the paper, she argued: “Overall, by early 2019, there will be substantial information available on the UK’s exit deal (if there is one), including the transition phase and the outline of the proposed future UK-EU27 trade deal.

“If Scotland did hold an independence referendum in March 2019, then Scottish voters would have more information on Brexit, and on the goals for an independent Scotland vis-a-vis the EU or EEA (European Economic Area), than they do now.

“But there would be some substantial uncertainty still and plenty of room for debate about the implications of the UK’s Brexit deal in 2019 and of the potential impacts — positive and negative — if an independent Scotland joined the EU or EEA and the risks it might fail in such an attempt.”

If the UK and the other 27 EU countries “agree and ratify a divorce deal within the two-year timetable” laid down by Article 50, Hughes said many details of this would be clear by March 2019, including over issues such as the rights of EU citizens living in the UK, the objectives of future trade deals between the UK and Europe and what transition arrangements will be put in place when Britain departs.

The UK’s Brexit transition phase will be “significant” to the debate over Scotland’s future, Hughes said. “If Scotland were to vote yes in March 2019 to independence, it would take at least 18 months or longer to become independent.”

A future indyref would include whether Scotland would have to commit to eventually joining the euro and if it would have to make an EU budget contribution without the UK rebate.

A Scottish Government spokeswoman said: “As the First Minister has made clear, the choice over Scotland’s future must be an informed one. That means that both the terms of Brexit and the implications and opportunities of independence must be clear in advance of the referendum.

“The First Minister will set out the next steps to parliament in the coming weeks as we continue our work to protect Scotland’s economy and our public services from the impact of Brexit.”