Image copyright Reuters Image caption Renewable electricity through cables going south of the border helped drive the increase in sales to the rest of the UK

Scotland's trade with the rest of the UK continues to be worth four times more than its exports to the EU, according to Scottish government figures.

The latest Export Statistics Scotland data showed the country sold £49.8bn to the rest of the UK in 2015 - £2.1bn more than the previous year.

Exports to the EU rose by £520m to a total of £12.3bn.

Both figures represented a 4.4% increase on the previous year.

The Scottish government is exploring options for keeping Scotland in the European single market after Brexit, with the first minister saying a second independence referendum is highly likely if it is felt to be the best option for protecting the country's interests.

Opponents argue that independence could threaten access to UK markets - a claim that is dismissed by the Scottish government.

The Scottish government said the increase in exports to the rest of the UK was driven by utilities such as electricity - largely from renewables - as well as gas and water, with petroleum and chemical products contributing to the growth in EU exports.

The statistics also showed that the total value of Scotland's international exports rose from £27.7bn in 2014 to £28.7bn in 2015 - of which £16.4bn was outside the EU.

The US continued to be Scotland largest overseas market outside of the EU, buying goods and services worth £4.6bn - more than any single EU country.

Within the EU, the Netherlands was again the largest market at £2.3bn - although the figure is inflated by Scottish goods going to the port of Rotterdam before being shipped elsewhere.

It was followed by France and Germany, which both accounted for £1.8bn of goods and services.

Scotland's trade Where was business done in 2015? 63% Rest of the UK 16% European Union 4.8% Food and drink

3.5% Professional & scientific

2.8% Petroleum & chemical

2.1% Mining & quarrying EPA

Scotland's economy secretary, Keith Brown, said it was "hugely encouraging" to see Scotland's total international exports, excluding oil and gas, increase by £1bn.

He added: "It is clear that since the vote to leave the European Union, we must continue to be seen to be a country that is outward facing and open for business.

"The EU market is eight times the size of the UK market, which highlights the importance of remaining in the Single Market.

"I want to be clear that Scotland should not face a choice between exporting to the EU or UK. We can do both."

Analysis by Douglas Fraser, BBC Scotland economy editor

The tussling over Brexit is back, with Scottish export figures that show two things, depending on one's perspective.

Conservatives emphasise the importance of sales from Scotland to the rest of the UK - four times greater than the value of sales to the rest of the EU in 2015.

But, points out the Scottish government, the size of the total European Union market is around eight times bigger than the size of the market across England, Wales and Northern Ireland.

To understand the difference, one side is measuring actual sales: the other potential for sales. Take your pick. They are, in a way, alternative facts.

What the export figures show us once more is that, unlike England and Wales, it is the United States that is Scotland's biggest single export market.

Read more from Douglas

Mr Brown also announced the members of the Scottish government's new trade board, which will have responsibility for helping to broaden Scotland's export base and grow exports beyond the country's traditional markets.

The board will include entrepreneur Russell Dalgleish, British Chambers of Commerce president Nora Senior and Ian Donnelly of Rosyth Babcock.

The UK government's Scottish secretary, David Mundell, said the figures showed that the domestic market in the UK was "far and away" the most important market for Scotland's businesses.

He added: "The Scottish government's own figures show our trade with the rest of the UK is worth four times our exports to the EU.

"Businesses in Scotland sold £37.5bn more in goods and services to their own market in the UK than they did to all 27 EU countries put together.

"Today's figures show the UK is the vital union for Scotland, and highlight the importance of maintaining the UK market and preventing any new barriers to doing business across the UK as we leave the EU."

Scottish Labour leader Kezia Dugdale said: "Tory plans for a hard Brexit risk damaging Scotland's economy - but the SNP government's own figures show that independence would be considerably worse.

"It is simply a reckless nationalist gamble to put access to the UK single market, and all the jobs that depend on it, at risk. That's why the SNP must drop plans for a second independence referendum."

Scottish Liberal Democrat MP Alistair Carmichael said the figures showed the importance of keeping Scotland in both the UK and the EU.

He added: "If Britain is to be pulled out of the single market and we put up barriers to our trade with Europe it would do huge damage to jobs and prosperity in Scotland.

"Similarly erecting a border between Scotland and the rest of the United Kingdom would result in a catastrophic loss in trade."

Who does Scotland trade with?

Quiz time: See how well you know the latest figures on Scottish trade