In the firmest comments yet on the Ipsos MORI survey, Scottish Secretary Alistair Carmichael said the findings would stay hidden as they were akin to confidential legal advice for ministers.
The Coalition has been facing demands to publish the poll all week since it emerged the Cabinet Office's devolution team spent £46,550 in January on "market research on attitudes in Scotland towards Scottish independence".
Following a letter to the Sunday Herald about the existence of the Ipsos MORI survey, a Publish The Poll campaign began online.
The Sunday Herald has also learned that the Cabinet Office has delayed answering a Freedom of Information (FoI) request about its polling on independence for the past two months, prompting criticism from the SNP.
Carmichael said the Government's private poll was consistent with published ones, which show a recent rise in support for a Yes vote.
He said: "Governments poll, it's no great secret. I think [the row] highlights the fascination some of the Yes side have with process rather than getting on and talking about the issues. Until anybody can point to anything that's improper then I don't see what the excitement's about."
Asked if the Government would ever publish the findings, he said: "No. There's an important principle here. The principle is it's government research and we don't release it. It's a bit like legal advice in that respect. This is not information that's been gathered with a view to it being published."
As the cost of the Cabinet Office poll was many times the price of a standard survey of 1000 people, Carmichael said that "might indeed" imply there was a very large, informative sample.
He also said the polling had been done to inform Westminster's Scotland Analysis series of papers on independence, which run to 1200 pages. He said: "It's been part of that analysis paper preparation. It's been closely linked to it."
SNP MSP Linda Fabiani said: "The longer the UK Government tries to keep this polling a secret the more embarrassing it becomes for the No campaign. That they are dragging their heels on an answer on a straightforward FoI request is disappointing but not very surprising.
"The simple fact is that the UK Government has spent nearly £50,000 of the public's money on this polling. In the interests of fairness and democracy they have got to publish the poll."