Seventeen per cent of Scottish adults would consider leaving the country if it becomes independent after the referendum in September.
A Panelbase survey for the Sunday Times and Heart radio found 700,000 people were considering leaving in the event of a 'yes' vote, compared to 200,000 people who would consider leaving in the event of a 'no' vote.
The survey put support for independence at 41%, up one since the last survey in May.
The 'no' vote was also up one on 48%.
Eleven per cent are yet to make up their mind. When they were excluded the 'yes' vote stood at 46% and 'no' at 54%.
Both sides welcomes the poll but it is likely to privately concern to Scottish independence campaigners.
Panelbase is one of the pollsters which typically finds a narrower gap in the polls when compared to YouGov, TNS or Ipsos Mori.
Historic examples of referendums around the world suggest the status quo tends to gain ground in the last few weeks of the campaign, as voters become more receptive to negative campaigning.
The Scottish independence campaign will have wanted a far smaller gap in the polls by this stage in the campaign.
Nevertheless, both sides welcomes the poll.
"Support for Yes is solid and as we move into the final eight weeks of the campaign we will be working hard to continue the flow of undecided voters to our side," Yes Scotland chief executive Blair Jenkins said.
"What this poll confirms is that, in spite of a renewed barrage of scaremongering and relentless negativity from the 'no' camp and Westminster government, we are in touching distance of success on September 18th. We need just over a four-point swing to put us in front."
Better Together campaign director Blair McDougall said: "This poll is a blow to Alex Salmond's faltering campaign and makes clear that the momentum is with those of us saying no thanks to separation.
"The closer we get to the referendum the more people are thinking seriously about the consequences of independence for the pound, pensions and our public services."
Thirty-four per cent of people said Scotland would be better off under independence, while 42% thought it would be worse off.
The stubborn 'no' camp lead on the economy is further bad news for the 'yes' campaign. Pollsters believed the remaining undecided voters are most affected by economic arguments.
The SNP reacted to the survey by pointing out that 700,000 people had already left Scotland over the last decade and used the poll finding to attack Westminster's immigration policy.
"People are leaving Scotland under the Westminster system. That's not based on a poll, it is what is actually happening," SNP MSP Stewart Maxwell said.
Alex Salmond has promised a more progressive immigration system in an independent Scotland.