Sturgeon urges all Labour voters to back independence

Her comments, which are likely to rile Scots Labour leader Johann Lamont, will be accompanied by an announcement of extra Scottish Government funding for food banks, calculated to highlight the impact of the UK Government's unpopular welfare reforms.

Ms Sturgeon, the "Yes minister" responsible for referendum strategy, will target Labour voters as polls show they are more sympathetic to independence than Conservative or LibDems' supporters, and are prominent among the one million or so Scots who remain undecided about the referendum.

She will say: "To every Labour voter in the country I say this - the Yes campaign is not asking you to change your party, instead it offers you the chance to get your party back.

"Independence will not mean the end of Labour but it might mean a rejuvenated Labour Party, a Labour Party free to make its own decisions, a Labour Party no longer dancing to Westminster's tune.

"For every voter with Labour in their heart, the message is clear: don't vote No to stop the SNP, vote Yes to reclaim the Labour Party."

Even during Labour's heavy 2011 Scottish Parliament election defeat, the party amassed 630,000 constituency and 523,000 regional votes.

In the previous year's Westminster election, more than a million Scots voted Labour.

Polls suggest about a quarter of Labour voters are in favour of independence.

Ms Sturgeon will also use her speech to announce an extra £1million of Scottish Government funding, over two years, to organisations providing foodbanks.

The move comes as new polls put the No campaign's lead in the referendum battle at six and 12 points respectively, after the 'don't knows' were excluded.

They also suggested the gap has stabilised after narrowing earlier in the year. A Panelbase survey for Yes Scotland put support for Yes on 40%; for No on 45%, and with 15% undecided.

Backing for Yes and No was down by one point compared with Panelbase's previous survey.

The findings equated to a 47%-53% split in favour of No, when undecided voters were excluded.

The poll also showed 53% of people would be prepared to vote Yes if they were persuaded independence would make them better off.

Blair Jenkins, the chief executive of Yes Scotland, said: "On these new figures, Yes just needs a three point swing to move ahead - and we are very confident of achieving success in September."

A second poll, by Survation, put support for Yes on 37%; for No on 47%, with 16% undecided. Support for Yes was down two points compared with Survation's March findings. The Yes/No split when 'don't knows' are excluded, according to Survation, was 44% to 56%.

Alistair Darling, head of the pro-UK Better Together campaign, said: "It is increasingly clear people in Scotland want to have the best of both worlds - a strong Scottish Parliament, with the guarantee of more powers, backed up by the strength, security and stability of being part of the UK."

Professor John Curtice, an expert in poll trends, said the surveys suggested the narrowing of the polls, witnessed since the start of the year, had halted. Looking ahead to the SNP conference, he wrote on the What Scotland Thinks blog: "Activists will be hoping Mr Salmond gives the speech of his life. It is certainly not an opportunity he can afford to waste."

First Minister Alex Salmond will make his address tomorrow afternoon. The slogan of the conference, the SNP's final gathering before the referendum, is "Forward". Senior SNP ministers will use the two-day event to promote the party's message that Scotland "can, should and must" leave the UK.

More than 1200 people, including party members, lobbyists and media are due to attend.

Among the resolutions, activists will welcome the publication of the SNP's independence White Paper and mark the 80th anniversary of the party by formally honouring past members who "tenaciously campaigned for Scotland's interests".