Britain's Queen Elizabeth II Sunday broke her silence on Scotland's upcoming referendum on independence, urging voters to "think very carefully." Buckingham Palace earlier had issued a statement indicating the queen would remain neutral.

Scots are set to vote Thursday on whether to end three centuries of unification with England. In the last week, British officials have issued warnings breaking up the United Kingdom could have a negative impact on defenses.

“You have an important vote on Thursday. Well, I hope people will think very carefully about the future,” the queen said Sunday, breaking with protocol to speak with well-wishers outside Crathie Kirk, a small church near Balmoral Castle where the queen is vacationing. The service included a prayer asking God "to save us from false choices," the Daily Telegraph reported.

The Mirror quoted a royal source as saying the queen "respects the will of the Scottish people and she will work with them, whatever the result. But she wants to make sure people have thought about the long-term repercussions of breaking up the union."

The remarks came as thousands of separatists demonstrated in Glasgow, Reuters reported. Scottish National Party leader Alex Salmond said on the BBC he's confident Thursday's vote will lead to an independent Scotland. Alistair Darling, head of the Better Together campaign, warned a split would spell economic doom.

Weekend polls indicated the vote will be tight. Prime Minister David Cameron was expected to head for Scotland this week to try to convince voters not to break up the union, the Associated Press reported. A "yes" vote would see Scotland split from the United Kingdom in 18 months but would have the queen serve as head of state anyway.