By Andrew MacAskill
LONDON (Reuters) - Scotland will need checkpoints along its border with England for the first time in more than three centuries if it votes for independence and rejoins the European Union, according to a think tank report published on Thursday.
The pro-independence Scottish National Party, which heads the Scottish government, wants to hold a second referendum on breaking away from the United Kingdom by the end of next year.
Voters in Scotland, which has a population of around 5.5 million, rejected independence in 2014. But Scotland's semi-autonomous government says Britain's departure from the EU, which was opposed by a majority of Scots, means the question must be put to a second vote.
If Scotland voted for independence, First Minister Nicola Sturgeon has stated a key objective would be to rejoin the EU.
The report by the UK In A Changing Europe think tank shows that while Brexit has reenergised the campaign for Scottish independence, it has made the consequences more complex. Any checks could create problems for Scottish businesses, which export three times more to the rest of the United Kingdom than to the EU.
Brexit has "profoundly changed the context in which independence is contested and could be realised", the authors of the report said.
An independent Scotland in the EU would be responsible for ensuring that all goods and services entering the country met the bloc's standards, according to the authors.
Border controls and inspection facilities would be needed along the main roads between Scotland and England with smaller roads potentially being monitored by cameras, the report said.
Recent opinion polls suggest Scotland is evenly split on the idea of independence, while pro-independence parties hold a majority in the Scottish parliament.
Sturgeon said last year that while Scotland would comply with all EU rules if her country joined the bloc, she would try to negotiate arrangements to keep free trade flowing with England.
The British government argued during the Brexit negotiations that the use of technology meant there was no need for checks on the border between the Republic of Ireland, an EU member, and Northern Ireland, which is part of the United Kingdom.
If there was another referendum and the Scots voted out, it would mark the biggest shock to the United Kingdom since Irish independence a century ago.
Scotland joined England in a political union in 1707, formally creating the Kingdom of Great Britain with a unified parliament in Westminster following centuries of antagonism and warfare.