THE result of the independence referendum hangs in the balance as a new poll shows both sides running neck and neck.

With nine days to go, the TNS poll suggested support for Yes and No was level at 41 per cent among those certain to vote after a dramatic surge in support for independence.

A further 18 per cent of people, equivalent to 600,000 voters, said they were undecided but would definitely vote on September 18.

Among those certain to cast their ballot, support for staying in the UK has fallen six percentage points while backing for independence has risen by the same amount over the space of a month.

Across the electorate as whole, the No campaign retained a wafer thin lead of one point.

Support for No was on 39 per cent, down from 45 per cent a month ago, while backing for Yes was on 38 per cent, up from 32 per cent. The undecideds are unchanged at 23 per cent.

Tom Costley, the head of TNS Scotland, said the polls showed "a remarkable shift in voting intentions". He said the outcome of the contest was now too close to call.

Blair MacDougall, Better Together's campaign director, said the poll showed the referendum had "got real", while Yes Scotland chief executive Blair Jenkins said the pro-independence campaign had the momentum.

The survey of 990 voters was conducted between August 27, two days after Alex Salmond's victory in the second live TV leaders' debate, and September 4.

It appears to confirm a huge swing to Yes over the past month, witnessed also in two recent polls by YouGov and Panelbase.

YouGov put Yes ahead 51 per cent to 49 per cent, excluding undecideds, at the weekend.

Panelbase put the No camp ahead by 52 per cent to 48 per cent, also discounting don't knows. All three surveys recorded a major surge in support for Yes and a drop in backing for No over the past month.

The TNS poll shows a big rise in people certain to vote, up from just over 70 per cent to 84 per cent, suggesting turnout could be higher than previous predictions.

The Yes campaign has made significant progress in persuading women to back independence and closing the gender gap between Yes and No voters.

Women backing Yes has risen from 27 per cent to stand at 35 per cent. Support for No has dropped from 49 to 41 per cent.

The only age group where the No campaign commands a majority is those over 55, for whom fears over pensions have proved an important factor. Of the over-55s, 49 per cent plan to vote No, against 31 per cent backing Yes.

According to TNS the Yes campaign enjoys a nine point lead among voters aged under 55, having overturned an eight point deficit a month ago.

Despite the dramatic rise in support for independence, 70 per cent of No voters believe Scotland will remain in the UK.

Yes supporters are less confident of victory, although 56 per cent think Scotland is poised to become an independent country.

Overall, 45 per cent predict a No victory, 31 per cent a win for Yes.

Mr Costley said: "This poll reveals a remarkable shift in voting intentions, but the signs were evident in our last couple of polls that indicated a narrowing of the No lead, especially amongst those who told us they were certain to vote. It is too close to call."

TNS's latest findings show a major shift from the long term trend in voting intentions. Over the past 12 months, support for No has hovered between 44 and 47 per cent, according to the pollster's main monthly sampling.

Yes support, at 28 per cent this time last year, has picked up since early July. Mr McDougall said: "The last couple of days will be seen as the moment the referendum got real.

"We know from these polls there is no room for a protest vote. The vote of any one of us could be crucial and could make the difference between the UK breaking up and staying together."

Mr Jenkins said: "This is another breakthrough poll that confirms Yes has the momentum.

"Last September the No lead was 22 points - now Yes has surged to draw level at 50/50, and our campaign has the wind in its sails."

Meanwhile, Better Together leader Alistair Darling and First Minister Alex Salmond are to go head to head again, this time on website Mumsnet.

They will take part in a webchat tomorrow, their latest tussle coming after a Mumsnet poll found more of its users in favour of Yes than planning to vote No.

This week's poll of the website's users found 48 per cent planning to vote Yes, 41 per cent for No and 11 per cent undecided.

Justine Roberts, chief executive and founder of Mumsnet, said: "Our Scottish users have been actively debating the referendum on Mumsnet.

"The issue of the economic viability of an independent Scotland has been raised far more frequently than individual household budgets in discussions, but the impact of independence on jobs, welfare, health and education are all areas of concern for Mumsnet users."

The website's survey also repeated similar findings that many Scots regard the pledge to block sharing of the pound as a "bluff".

A total of 61 per cent of those who took part in the survey said they thought Scotland would be allowed to keep the pound, in a currency union with the rest of the UK, if Scotland were to vote Yes and become independent.