Support for Scottish independence is at its highest level in the annual Scottish Social Attitudes Survey.

The study, which has been conducted since 1999, found support for independence at 46% when people are asked to choose between devolution, having no parliament and leaving the UK.

It is the highest support registered for independence since the survey began in 1999 and double the level of support for independence the survey registered in 2012, which was 23%.

The results show a considerable age gap in those who support independence and those who support staying in a devolved United Kingdom.

Of those polled who were aged between 16 and 24, 72% backed independence. This compares with just 26% of those aged 65 and over.

Despite the yearly survey's findings, two separate opinion polls released on Wednesday show support for the union in the lead if a fresh referendum was held.

The report's author, Professor John Curtice, said: "The nationalist movement in Scotland has never been stronger electorally.

"Meanwhile, from its perspective, the outcome of the EU referendum appeared to be a perfect illustration of their argument that for so long as it stays in the UK, Scotland is always at risk of having its 'democratic will' overturned by England.

"However, the commitment to the EU of many of those who voted to remain does not appear to be strong enough that they are likely to be persuaded by the outcome of the EU referendum to change their preference for staying in the UK.

"Meanwhile, there is a risk that linking independence closely to the idea of staying in the EU could alienate some of those who currently back leaving the UK."

The report found increasing levels of eurosceptism among the Scottish public despite the country's 62% vote to stay in the European Union last year.

When presented with a series of options for the UK, a quarter of respondents wanted to leave the EU while a further 42% said the country should stay in but Brussels should have its powers reduced.

Just 21% said the relationship should stay the same while only 7% thought the organisation should either get more powers or become a single continental government.

Mark Diffley, from polling company Ipsos MORI, said: "This is significant and in line with recent polling despite the earlier fieldwork dates.

"This is undoubtedly good news for the First Minister and for independence campaigners.

"We are in line for a tight race as and when the referendum really gets under way."

SNP MSP Bruce Crawford said: "It is no surprise that more and more people in Scotland are now supporting independence as the promises made to Scotland in 2014 are systematically unpicked by the UK Tory government.

"There is a cast-iron democratic mandate for a referendum, and the First Minister has set out a plan to give Scotland a choice, when the options become clear, between a hard Brexit and becoming an independent country."

Scottish Conservative constitution spokesman Adam Tomkins said: "This report shows there is significant division already across Scotland on a range of constitutional matters.

"Sparking yet another referendum will only make this worse.

"The people of Scotland do not want another referendum, and would prefer the SNP got on with dealing with the things that matter."