About two-thirds (66%) of English people living in Scotland intend to vote No on September 18 compared with 42% of Scots, a Panelbase poll for the Sunday Times and Heart Radio found.
Independence is the most popular choice amongst Scots, with 44% intending to vote Yes compared with just 27% of English people, the poll suggests.
But the weight of non-Scottish votes is enough to sway the vote towards No with overall support for keeping the UK at 47% compared with 40% for Yes, according to the poll.
Meanwhile, a separate poll has put support for independence at its lowest point since last September.
Only 34% of people surveyed by ICM for the Scotland on Sunday support independence, down five points since the last ICM poll in April. Support for the UK is up four points from last month to 46%.
Better Together has also gained ground amongst Panelbase participants, rising two points to 47% from the last Panelbase poll, which was conducted for Yes Scotland in April, while Yes held steady at 40%.
Support for Yes is now 46% according to Panelbase and 42% according to ICM once undecided voters are excluded.
When undecided Panelbase participants were pressed to say how they would vote today, Yes gained ground slightly rising one point to 47%.
Yes Scotland said the latest polls indicate that "a Yes vote is within reach".
Independence is up three points from the last Sunday Times/Heart Panelbase poll in February while "average monthly support for Yes has been rising steadily" across all polls since the publication of the Scottish Government's white paper on independence, Yes Scotland said.
Yes Scotland chief executive Blair Jenkins said: "With precisely four months until the independence referendum, it is all to play for.
"The Yes movement has made big gains over the last six months and we are confident the upward trajectory of Yes will continue through to September.
He added: "There is a long way to go and a lot of hard work to be done.
"We are looking forward to that. We are confident that as more and more people engage in the debate they will see through the shallow negativity of the No campaign and seek real information about what independence will mean to them.
"The realisation will continue to grow that Scotland can, and should, be a fairer and more successful independent country, with the benefits shared by all, and the result on September 18 will reflect that."
:: Panelbase interviewed a representative sample of 1,046 adults resident in Scotland on May 8-14.
:: ICM Research interviewed an online sample of 1,003 people living across Scotland on May 12-15.
Better Together campaign director Blair McDougall said: "When even the SNP's favourite polling company Panelbase is showing the nationalists going backwards, then you know they are in trouble.
"As the referendum gets closer more Scots are starting to think seriously about the big issues - like what would replace the pound, how our pensions would be paid and what would happen to the funding for our schools and hospitals.
"It's no surprise that as people look at these issues in detail they are overwhelmingly rejecting separation.
"What's clear from today's ICM poll is that Alex Salmond has a problem with women.
"Scottish women have seen right through his attempts to bribe them into voting for the risk and uncertainty that separation would bring."
The SNP rejected what they described as a "concerted attempt to foster division in Scotland" by linking voting intentions to national identity.
SNP Westminster leader Angus Robertson, who is half-German and was born in Wimbledon, said: "At all levels of politics, the SNP is represented by those either born in England or with strong connections to England.
"Throughout this campaign there seems to have been a deliberate attempt from some to try and paint the referendum as being about identity. We reject that wholeheartedly."
English-born SNP MSP Nigel Don said: "It is not about identity - it is who is best placed to make decisions for Scotland. We believe that is the people living in Scotland.
"Scotland has been hugely enriched as a nation through those who have come here to live and work and raise their families - from England and further afield."
SNP MEP candidate Tasmina Ahmed-Sheikh, was born in London to an Indian-born father and a Welsh-Czech mother, said: "The late Bashir Ahmad, Scotland's first Scots-Asian MSP, said 'it isn't important where you come from, what matters is where we are going together as a nation'.
"As we approach the referendum, the Asian community in Scotland is definitely moving towards independence."
Scottish Labour constitution spokesman Drew Smith said: "These polls are damaging for Alex Salmond's campaign to break up Britain and he will hope they are not evidence of what Jim Sillars warned of last week - that the First Minister is a liability for their campaign.
"It also shows that despite lottery millions and more on the cards from Brian Souter, Scots want to see detail and have honest answers, both of which are an anathema to the SNP's campaign.
"As the referendum draws nearer and Scots are asked to focus on the big issues, they will listen more closely to the employers as well as the experts who make clear that separation will harm Scotland and see that the SNP's sums simply don't add up.
"Alex Salmond likes a gamble, but it is becoming clearer that Scots certainly don't."