Millions of Britons begin voting in historic EU referendum that will shape British-EU ties for generations.
Millions of Britons are heading to the polls to vote on whether the UK will remain a part of the European Union.
A record 46.5 million voters have signed up to weigh in on Thursday's referendum that asks: "Should the United Kingdom remain a member of the European Union or leave the European Union?"
The divisive referendum has sparked the greatest emergency in the EU's 60-year history.
The vote pits the Remain campaign, backed by British Prime Minister David Cameron and Labour Party leader Jeremy Corbon, against the Leave camp, led by the former London mayor, MP Boris Johnson.
Polling stations opened at 7am (06:00 GMT) and will close 10pm (21:00 GMT) local time.
There are no official exit polls because polling experts say the lack of recent comparable votes in Britain could make the results less reliable.
Results from polling will, however, be released after the ballots close.
Too close to call
On the eve of the historic vote, two polls – both conducted over the internet – put the Leave camp ahead by one or two percent. But a telephone poll gave Remain a sizeable lead of 48 percent, ahead of Leave with 42 percent.
Standing outside a fish-packing plant a day before the referendum, Leave camp leader Boris Johnson argued it was time to take back control of the UK's industries.
"You take back control and I think it will be a big big moment for democracy in this country and around Europe," said Johnson.
Desperate to inject some pro-Europe passion late in the day on Wednesday, the prime minister and his allies made appeals to older voters, urging them to think of their children, rather than their own nostalgic views of their country.
"Think of one word that brings it all into one, which is 'together', because frankly if we want a bigger economy and more jobs we're better if we do it together," said Cameron.
"If we want to fight climate change, we're better if we do it together. If we want to win against the terrorists and keep our country safe, we're better if we do it together."
The Remain camp has said a British exit would be hugely destabilising in terms of security and the economy.
Supporters of the Leave campaign argue a Brexit would be for the best, with much of its campaign focused on tighter border controls and freedom from EU regulations on immigraton and the economy.
"If we destroy the European Union, which for all its faults has nevertheless delivered a tremendous amount of cohesion within our continent, I think the consequences of that are fairly unpredictable. So for that reason, I don't think that's something we should wish for," Conservative MP and Remain campaigner Dominic Grieve told Al Jazeera.
'Out is out'
EU leaders have warned there will be no turning back from a vote to quite the 28-member bloc.
"Out is out," European Commission chief Jean-Claude Juncker said in Brussels, dismissing any chances of a post-vote renegotiation of Britain's EU membership terms.
French President Francois Hollande has said an exit by the UK would be "irreversible".
The referendum has raised concerns across Europe that a British withdrawal could trigger a domino effect of exit votes and threaten the integrity of the bloc, already under severe strain from Eurozone and migration crises.
Even if it stays, the status quo will not be an option.
"Whatever its result is going to be, we must take a long hard look at the future of the union. We would be foolish if we ignored such a warning signal as the UK referendum," EU President Donald Tusk warned this week.
Tusk has previously said that a British leave vote could lead to the "destruction of not only the EU but also of Western political civilisation".
The EU was created after the Second World War as an antidote to the nationalism which had devastated the continent. The movement for unity was led by France and Germany.
