BOTH sides have claimed momentum going into the final few days of the referendum race, after the latest poll suggested the No campaign retained a wafer- thin lead.

The ICM/Guardian survey put support for No on 51 per cent and for Yes on 49 per cent, discounting undecided voters. With all voters included, No was on 42 per cent and Yes on 40 per cent - but with 17 per cent undecided the outcome of Thursday's vote remains too close to call.

The headline figure suggested a continuing surge to Yes, after ICM's previous poll last month gave the No side a clear 12-point lead, discounting don't-knows.

This came hours after a YouGov Times/Sun poll put the No campaign in the lead by 52 per cent to 48 per cent. The result was a reversal of the organisation's poll a week ago which showed Yes in the lead by two points.

A new poll of polls, taking the latest sets of findings into account, put No in the lead by 51 per cent to 49 per cent.

It means the No campaign's lead has been cut to its lowest ever margin in the regularly updated poll of polls, which is published on the What Scotland Thinks website.

Yesterday's ICM poll highlighted the importance of Labour's effort to shore up No support among its voters.

It showed 29 per cent of those who supporter Labour at the last Holyrood election and 42 per cent of those who backed the party in the previous year's general election planning to vote for independence.

Among those who voted for the SNP in its landslide election victory three years ago, 91 per cent are voting for independence.

The two new surveys were conducted between Tuesday and Thursday, as David Cameron, Ed Miliband and Nick Clegg abandoned Prime Minister's Question Time at Westminster to make unscheduled visits to Scotland.

Their "lovebombing" campaign coincided with stock market falls and a series of stark economic warnings as five banks confirmed plans to register their HQs in London on a Yes vote.

Yes Scotland said the latest poll showed the onslaught had failed to halt rising support for independence. Campaign chief executive Blair Jenkins said: "It shows the barrage of intimidation from the No campaign isn't working. David Cameron's co-ordination from Downing Street of big business to talk down Scotland has been met with a giant raspberry, particularly among Labour voters."

Blair McDougall, the Better Together campaign director, said interventions by the banks and supermarkets, which have warned of rising prices in an independent Scotland, had "brought home the huge risks of separation".

He added: "This is the third poll in a row to show the No campaign in the lead, but this fight for the future of Scotland will go right down to the wire.

"There is no room for a protest vote in the referendum."

Insiders from both camps claimed the momentum was with them as the campaign enters its final stages.

Yes Scotland is set to pitch an emotional message, telling voters independence is within grasp and urging them not to be "bullied" by economic warnings.

Better Together will continue to put Labour heavyweights, including Gordon Brown and John Reid, at the heart of its campaigning.

Some 87 per cent of those ­questioned by ICM said they were "absolutely certain to vote" in the latest indication turn-out will be high.

Support for independence was strongest among Scots aged 25 to 34, who said they would vote Yes by a margin of 57 per cent to 43 per cent.

Those aged 65-plus backed No by 61% to 39%.

The poll suggested the gender gap between Yes and No supporters will be crucial to the outcome, with women wanting to remain in the UK by 55 per cent to 45 per cent, compared with a majority for independence among men of 52 per cent to 48 per cent.

Asked about independence, just over one-quarter of Scots (26 per cent) described leaving the UK as "a huge risk" while 13 per cent saw it as "no risk at all".