Former SNP leader Gordon Wilson has said some Nationalists, who strongly support staying in the European Union, might vote for a British exit in the hope of boosting the chances of gaining independence for Scotland.

Mr Wilson said that might lead to some of its supporters supporting a "Brexit" in hope of boosting Scotland's secessionist aspirations.

It came after former prime minister Tony Blair warned this week the United Kingdom could break up if Britons voted to leave the EU when a referendum is held before the end of 2017.

Mr Wilson said he was still weighing up how best to vote himself.

"The SNP has a huge hinterland which may get impatient if it doesn't progress the leadership (towards independence)," Wilson, who led the party in the 1980s, told Reuters.

"I myself haven't decided how I'm going to vote (in the EU referendum). I helped steer the SNP towards European policy (in the 1970s) but certain things have happened and ... I want to look at it strategically from the Scottish viewpoint. It depends on an analysis of how Scotland can better achieve independence."

Nicola Sturgeon, the leader of the SNP and of Scotland's devolved government, has said she supports staying in the EU, and polls show that a majority of the 5 million Scots would also back that view.

However, the Scottish vote is dwarfed by that of England which has 53 million and represents about 84 percent of the population of the United Kingdom.

With opinion polls surveys suggesting the EU vote will be very close, Scottish nationalists backing a Brexit could help tip the balance, even if a majority in Scotland still voted to remain in the bloc.

Sturgeon has said that if Scots voted to stay but the majority of Britons voted to leave that could trigger another independence referendum on Scottish independence.

Scots rejected independence by 55-45 percent in a vote in 2014 but since then the SNP has gained further strength, taking 56 of the 59 seats representing Scotland in the national parliament in London in last May's election.

However, the SNP's support for the EU does leave it with a paradox, Wilson said.

"One of the problems the SNP has in supporting Scotland staying in (the EU), is that they have to say 'stronger in Europe' and that's the mirror image of the (unionist) 'stronger in Britain'," Wilson said.

Sturgeon has previously said there could only be another independence vote if a majority of Scots voted for a party which proposed one in a Scottish parliamentary election. Such an election is due in May this year and polls indicate that the SNP will be easily returned to power.

But Wilson said another vote on independence should be some time off to ensure that the economic arguments, unconvincing at the last vote, were the right ones this time, less focused on North Sea oil and more on developing skills in Scotland.

"Until you ratchet up support to 60 percent you shouldn't have another referendum," he said.

"What will happen after dare-I-say-it the distraction of the (May) Scottish assembly election is a resumption of campaigning for independence."

Wilson has no formal role in the party but runs an independence think tank called Options for Scotland.