UNDECIDED voters in SNP heartland areas are three to four times more likely to back a No vote than a Yes, according to the pro-Union campaign yesterday.

Better Together said it canvassed more than 1000 previously undecided voters in each of the six Westminster seats held by the SNP, and in five seats held by Alex Salmond and SNP ministers.

In the Westminster seats, it reported an average of 58% of formerly undecided voters choosing No, compared with an average of 14.8% backing a Yes.

It reported the highest movement to No in Moray, the constituency of SNP Westminster leader Angus Robertson, with 68% of undecided voters backing the Union, and 13% saying Yes.

In Holyrood seats held by Salmond, Nicola Sturgeon, Alex Neil, Mike Russell and John Swinney, an average of 53% of formerly undecided voters chose No and 16.8% Yes. The biggest difference was in Salmond's Aberdeenshire East constituency, where Better Together reported undecided voters at 57% for No and 15% for Yes, with 20% still unsure.

Blair McDougall, Better Together's campaign director, said: "The latest data shows us well ahead in all the areas where you would expect the Nationalists to be turning out their core vote. We think Scotland will vote strongly No."

But the SNP claimed the figures were made up. Bruce Crawford MSP said: "The No camp don't have enough people on the ground to do proper canvassing in these seats."