NICOLA Sturgeon has challenged the leaders of Scottish Labour and the Liberal Democrats to abandon their opposition to a second independence referendum.

The First Minister said Kezia Dugdale and Willie Rennie should back a re-run of last year's vote if there was a "material change in circumstances" or an upsurge in support for independence.

She was responding to comments from both leaders saying they would not stand in the way of MSPs or party members campaigning for independence if a second were held.

Ms Sturgeon issued her challenge during a speech to the Scottish Parliamentary Journalists' Association in Edinburgh.

Ms Sturgeon said the recent comments by Scots Labour leader Ms Dugdale and the Lib Dems' Mr Rennie "shows they know, as well as we know, what way the wind is blowing over the medium to longer term".

She said: "The debate about independence goes much further than the SNP.

"Clearly, As Kez and Willie are now conceding, it goes into the hearts of Labour and the Liberals as well.

"If they are to be taken seriously about what they have said, and if what they have said is to be credible and coherent, then they have to take it to its logical conclusion.

"It's not going to cut much ice with supporters of independence in their own parties to say in one breath, if there is another referendum you can stand up for what you believe in, but in the next breath say, but we think a referendum should be ruled out forever and a day."

She added: "I issue a challenge to Kezia and Willie.

"I say to them, if opinion doesn't significantly shift from the referendum or if there is no material change in circumstances from the ones that prevailed last year, it wouldn't be right to propose a second referendum

"But do they agree with me on the converse?

"If we do see opinion shift or if we do see a material shift in circumstances, surely they must agree it would be equally wrong for any one politician to rule out a referendum indefinitely."

She also repeated the SNP's call for new Labour leader Jeremy Corbyn to back the devolution of trade unions laws as a means of neutralising planned Conservative reforms in Scotland.

The Nationalist leader indicated her party would not share a platform with other pro-EU politicians, including Scots Tory leader Ruth Davidson, in the forthcoming In/Out referendum on Britain's membership.

She said she aimed to win another SNP majority at next year's Scottish Parliament elections and revealed she has set her party the task of knocking on half a million doors before Christmas to get the campaign "firing on all cylinders"

Ms Sturgeon, who plans to set out possible triggers for a second referendum in the SNP's election manifesto said the party was considering the lessons from its defeat last year but insisted the Scottish Government was not actively planning for a re-run.

She said: "We have been and will continue to think about all aspects and issues that were in play in the referendum, what worked and what perhaps we didn't do as effectively.

"What were the barriers to people voting Yes that if we were ever in another independence referendum we might want to do differently?

"Of course, currency was one of those issues.

"I've always said, though, where I would agree with someone like Jim Sillars is, yes, currency was a difficult issue for us in the referendum campaign.

"Where I disagree is that if we only had a different position on currency - if we'd proposed a different Scottish currency, for example - then somehow currency would not have been a difficult issue.

"That's always going to be a difficult issue."

In a warning to the SNP's opponents, she added: "In my experience those who voted Yes last year, by and large continue to support independence and they will continue to support independence in all circumstances because they have decided, out of a process of deep consideration, that's the best future for Scotland."

Discussing her recent appearance in Vogue, the fashion magazine, she also told journalists she was "internally conflicted" about media interest in her image and how she should respond.

A Scottish Labour spokesman said: "The Bourne films will always be on ITV; QI will always be on Dave; and Nicola Sturgeon will always be on about another referendum. Scotland is fed up with repeats."

A Scottish Lib Dem spokeswoman said: "Another day, another attempt to distract people from the SNP’s record on GPs, the police and school standards."