EDINBURGH -- Two opinion polls show that Scotland's voters are narrowly divided on whether to leave the United Kingdom one month before a referendum.

Sunday's published polls both found that a majority of decided voters want Scotland to stay within the UK alongside England, Wales and Northern Ireland.

But they found support for independence growing ahead of the Sept. 18 vote -- and still-undecided voters holding the balance.

A poll for the Scotland on Sunday newspaper put support for UK membership at 47 per cent, up 2 points; support for independence at 38 per cent, up 4 points; and undecided voters at 15 per cent.

Another survey commissioned by the pro-independence campaign found 46 per cent support for the UK, 42 per cent for independence, and 12 per cent undecided.

Both had error margins of 3 percentage points.