EDINBURGH, Scotland — 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. 15 vote — and still-undecided voters holding the balance.

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

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

Both had error margins of 3 percentage points.