While the outcome looks too close to call, the pro-independence camp has seen support surge in recent weeks as the "No" side's long-term lead in the opinion polls shrivelled away.

 

"This is our opportunity of a lifetime," Scotland's pro-independence First Minister Alex Salmond told a cheering crowd of supporters in Perth at a final rally on Wednesday.

 

"It's the greatest, most empowering moment that any of us will ever have," he said, as supporters waved Scottish flags and chanted "Yes we can!"

 

British Prime Minister David Cameron has pleaded with Scots to vote in favour of staying in "our home" and has warned that the break-up would be a "painful divorce" full of economic uncertainty.

 

If Scots vote "Yes", it would end a union dating back to 1707, could force Cameron to resign and might raise serious questions about Britain's status on the international stage.

It is being closely watched in other parts of the world with strong separatist movements, particularly in the Spanish region of Catalonia where many are now also clamouring for a vote.

 

World financial markets have been volatile for days on uncertainty over the outcome.

 

And US President Barack Obama, leader of Britain's closest ally, weighed in Wednesday saying he hoped the UK would remain "strong, robust, united".

 

A record turnout of around 80 percent is expected in the referendum after 97 percent of people eligible to vote registered, almost 4.3 million people.

 

Polling stations close at 21:00 GMT and results are likely to emerge in the early hours of Friday.

 

At a polling station in Edinburgh West, one of 2,600 places where votes will be cast across the country, people arrived almost as soon as the booths opened at 0600 GMT.

 

"It's a very special day, one in a lifetime," said presiding officer Peter Macvean.

 

Questions over whether an independent Scotland could be a member of the European Union and how long this would take to negotiate have surfaced repeatedly.

 

Scotland's Parliament, opened in 1999, holds some powers devolved from Westminster to set policy in certain areas of domestic policy, such as health and education.

 

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