LONDON -- The British pound slipped sharply after an opinion poll showed that those advocating Scottish independence from the United Kingdom have gained ground, a little more than two weeks before the vote.

A YouGov poll released Tuesday showed support for Scottish independence running at 47 per cent. As a result, the 'no' camp -- those supporting the continuation of the 307-year union with England, Wales and Northern Ireland -- only has a 6 per cent lead in the poll.

That represents a significant narrowing in the 'no' lead. Less than a month ago, the equivalent poll lead was over 20 points.

The narrowing echoes other findings that the 'yes' campaign has gained ground over the past week or so after its leader, Scotland First Minister Alex Salmond was widely judged to have bested Alistair Darling, the head of the "Better Together" campaign, in a televised debate.

"A close finish looks likely, and a 'yes' victory is now a real possibility," said Peter Kellner, YouGov's president. "Even if 'no' finally wins the day, it now looks less likely that it will win by a big enough margin to deliver a knockout blow to supporters of independence."

The poll, which was based on interviews with 1,063 people, spooked some traders, and the pound traded 0.6 per cent lower at $1.6525. The Scottish independence vote takes place Sept. 18.

"With less than three weeks to go until polling day the tide is starting to shift," said Kathleen Brooks, research director at Forex.com.

The economic impact of a vote in favour of independence remains difficult to quantify as many aspects remain unclear, such as whether a go-it-alone Scotland would be able to use the pound as its currency, as the "yes" campaign advocates. There are also questions as to how the U.K.'s debt mountain would be divvied up.

"We think that the prospect of independence could boost volatility in the pound in the coming weeks," Brooks added.

Scotland already has a parliament responsible for a wide array of social matters as well as its own legal code. However, economic and defence matters remain the responsibility of Westminster in London, where Scottish lawmakers make up a minority. The main U.K. political parties have indicated that they are prepared to give the Scottish Parliament more powers after the vote.