Campaigners wave Scottish Saltires at a 'Yes' campaign rally in Glasgow, Scotland. Photo Reuters/Dylan Martinez

The No campaign has retained a narrow lead ahead of tomorrow's Scottish independence referendum, according to the latest opinion polls.

A YouGov survey for The Sun and The Times found 52pc of Scots are to vote for the union, with 48pc favouring independence when undecided voters are excluded.

The result was mirrored in a Panelbase survey, which also found 52pc of Scots back the union compared to 48pc for independence, again when undecided voters are excluded.

A survey by Ipsos-Mori for the broadcaster STV suggests the gap could be even closer.

It found 51pc of people are voting No, with 49pc backing Yes, when undecided voters are excluded.

When those who are yet to make up their mind are factored in, the No campaign is on 49pc, Yes on 47pc and 5pc said they do not know how they will cast their ballot.

The YouGov result released tonight remains unchanged from the last poll it conducted six days ago.

It excludes the "don't knows", who made up 6pc of the survey.

It said its research also suggests men are more likely to vote for independence by a margin of 54% to 46%, while women would prefer Scotland to remain in the UK by a margin of 57pc to 43pc.

YouGov said the result was compiled after 3,237 electors were questioned between September 15 and 17.

The Panelbase survey came out less that 24 hours before voting gets under way in the referendum and was another indication that the campaign over the future of the UK could go down to the wire.

Exactly half (50pc) of the 1,004 people who were questioned said they would be voting No to independence, with 45pc voting Yes.

Just one in 20 (5pc) of voters have still to make up their mind, according to the research.

It added men continue to be more likely to support Scotland leaving the UK, with 54pc of all males who were questioned said to be Yes voters, ahead of 44pc who are voting No and 3% who are undecided.

Just under two-fifths (39pc) of women questioned said they would be voting Yes tomorrow, with 54pc backing No and 7pc still undecided.

Survation also released its final poll on the referendum tonight, which suggested 53% of voters will support Scotland remaining in the union while 47pc will vote Yes - when undecided electors are excluded.

When the 9pc of those unsure how they are voting are included, the No campaign received 48% while Yes picked up 43pc.

The poll for the Daily Record was conducted by telephone over a 24-hour period on September 16 and 17.

Survation said the poll managed to reach 1,266 respondents but has an effective sample size of 1,089.

PA Media