SIR Ian Wood, the North Sea oil tycoon, has urged Nicola Sturgeon not to call a second independence referendum, as the SNP continued to prepare the ground for a re-run of the 2014 vote.

The businessman warned Scotland would face a lengthy and uncertain process to join the EU as a member state in its own right and, even then, would enjoy "very little influence" in Brussels.

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His comments came as the SNP continued to press the case for independence, despite putting a long-promised summer campaign on the back-burner.

The Herald's sister paper, the Sunday Herald, revealed the drive had been delayed until the autumn amid uncertainty over the SNP's position on key policies such as the currency an independent Scotland might use.

Nevertheless, in an intervention with an eye firmly on a future independence campaign, Angus Robertson, the party's Westminster leader, claimed Scotland had been "ignored, outvoted or overruled" in a dozen key decisions over the past 12 months.

They included the result of the 2015 General Election and June's EU referendum.

"Scotland faces a deep, growing and increasingly obvious democratic deficit at Westminster as our politics continue to diverge from the rest of the UK," he said.

Mr Robertson, a candidate in his party's deputy leadership contest, hit out as it emerged grassroots pro-independence groups were set to step up campaigning in the absence of an official SNP initiative.

But wharning against another referendum, Sir Ian told a Sunday newspaper: "We've got to give very careful thought to being a small independent member of the EU.

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"It is one thing to talk about whether the UK is in Europe or not. It's another thing entirely to say Scotland should be on its own in the EU."

He said Scotland would enjoy little of the UK's former influence within the EU.

"Scotland would have to vote for independence and then apply to join the EU and this is a long process and one that would be damaging, with a lot of uncertainty for the oil and gas industry.

"Also, in voting for independence, we would not know what the conditions of our European entry would be.

"I was in favour of remaining in the EU.

"I have this idea we are becoming too divisive in the world. Everyone wants to be independent but I think bigger economic units are more successful.

"We actually have to be better at living and working together."

His comments were welcomed by Murdo Fraser, the Scots Tory MSP, who said: "Sir Ian Wood is speaking for many many families and firms across Scotland who know that our future is more secure as part of the UK family of nations.

"The SNP's position is to argue that because we are leaving the EU, we should also leave the UK - even though the UK market is four times more important."

He added: "The Nationalists now need to put their blinkered obsession with independence to one side and focus on ensuring the UK as a whole gets the right deal as we leave the EU."

Meanwhile, Kezia Dugdale, the Scottish Labour leader to underline her party's opposition to a second independence referendum after Alex Rowley, her deputy leader, said he would not oppose another plebiscite.

She threatened to take disciplinary action against MSPs who rebelled against the party's recent election pledge to vote against a second independence poll.

Ms Sturgeon has said a referendum is "highly likely" following Brexit and has ordered Holyrood legislation facilitating the vote to be drawn up.

A source close to Ms Dugdale said: "The party's view is that it would be a whipped vote and Alex and all other MSPs would be expected to oppose it.

"We committed in our manifesto to vote against a second independence referendum in the lifetime of this parliament.

"We won't be changing that policy any time soon."

READ MORE: First Minister Nicola Sturgeon sets out her five Brexit demands for Scotland that may determine possibility of second independence referendum

Jackson Carlaw, the Scots Tories deputy leader, welcomed the move but insisted Labour's opposition to an independence vote remained "half hearted".