EU nationals will lose their right vote in a new independence referendum if it takes place after Brexit, two leading experts have warned in an article for a European think tank.

In a joint blog on a pro-EU website Richard Marsh and Fabian Zuleeg have said that the group are unlikely to be included in the franchise should the plebiscite take place after the end of March next year.

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Research has suggested EU nationals are among a key section of the population identified as having switched from voting No in 2014 to saying they would support Yes in a new referendum.

But in a piece for the Scottish Centre on European Relations, Marsh and Zuleeg pointed out one of the consequences of leaving the EU was that these residents may no longer be allowed to vote.

“EU citizenship gives every EU citizen the right to vote for and stand as a candidate in municipal and European Parliament elections in whichever EU country the citizen resides. The way the franchise was constructed in the Scottish independence referendum in 2014 used this as the basis and thus conferred the right to vote to EU citizens resident in Scotland at the time,” they explained.

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“Unless there are major changes to the way this franchise is constructed, it implies that EU nationals could vote in a future Scottish independence referendum if the UK is still in the EU at that point.

“However, if the UK has already left, most likely, EU citizens will not have the right to vote in any UK election or referendum. In effect, this would exclude a significant proportion of the current electorate from a future Scottish independence referendum.”

The two men went on to suggest that even if a new referendum was held during a post Brexit transition period, which may last until the end of December 2020, it was likely EU nationals would not be allowed to vote.

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They added: “This transition period will effectively be a stand-still period, i.e. EU rules and rights will still apply. However, politically, the UK will no longer be part of the EU institutions, implying that UK citizens will no longer vote for the European Parliament. At the same time, EU citizens in the UK are likely to lose their voting rights.”

Their intervention raises the question whether the First Minister may press ahead with a second referendum, after last year suspending her original plans for a vote between Autumn this year and Spring 2019.

In June last year she told MSPs she would update parliament on her thinking once the situation had become clearer as to what type of relationship the UK was pursuing with the EU. The update was expected in Autumn this year.

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However, in an ITV interview yesterday she said she may not have clarity by then – raising the possibility whether she may progress with plans ahead of then.

“I become more and more doubtful that by the autumn of this year we are going to be any further forward to knowing what the future relationship is than we are at the moment,” she told Peston on Sunday.

Mairi Gougeon, the SNP MSP, hit out at the prospect of EU nationals losing their vote.

“The SNP believes that anyone over the age of 16 who chooses to make Scotland their home, should have the right to vote in all elections,” she said.

“Through their chaotic handling of Brexit, the Tories have made it perfectly clear that they don’t give a damn about EU citizens living and working in our communities. And to actually deprive them of certain democratic rights in the process is shameful.

“The Scottish Government is consulting on extending the franchise for Scottish Parliament and local elections. Despite the increasingly hardline, extreme rhetoric emanating from the Brexiteers, it’s important that we continue to send the message that Scotland is an inclusive nation that believes in equal rights.”

A report last year for the Scottish Centre on European Relations, found the votes of EU nationals could help swing a 51 per cent vote for Yes.

The study cited a report by the Scottish Parliament Information Centre (SPICe) that showed there were 181,000 EU nationals living in Scotland in 2015. Further data published by the Office for National Statistics (ONS) showed the figure had increased to 219,000.

Marsh and Zuleeg concluded: “The cohort of EU nationals in Scotland is continuing to grow and, most likely, will continue to increase during the transition period, however long it might last in the end. But if there is a Scottish independence referendum during the transition period, these EU citizens will, most likely, be excluded from voting.

“Given the number of people involved, this might well have a material impact on the outcome of such a referendum, reducing the chance of a vote for Scottish independence.”