Fast Facts

Britain votes on Thursday to decide whether to remain in or leave the EU

Polls show a tight race expected

Remain camp accuses Leave rivals of scaremongering on immigration issues

Leave campaigners say EU is costing the UK too much

Rival sides in Britain's referendum on European Union membership have made final appeals hours before the crucial vote.

Outlining his vision of a future with Britain retaining its position in the 28-nation bloc, Prime Minister David Cameron bristled at the notion that the country would be headed in the wrong direction if the "Remain" side prevailed in Thursday's vote.

"We are not shackled to a corpse," Cameron told the BBC. "You can see the European economy's recovery. It's the largest single market in the world."

Watch: Brexit: Britain at the crossroads

Pushing for a British exit, or Brexit, the most notable figure on the "Leave" side, former London mayor Boris Johnson, mugged for the cameras at the Billingsgate Fish Market in East London and pretended to kiss a fish — a not-so-subtle reminder that this is an island nation that takes great pride in its independence and self-assurance.

"It's time to break away from the failing and dysfunctional EU system," Johnson said. "It's time to have a totally new relationship with our friends and partners across the Channel."

A day earlier, Johnson, a member of Conservative Party, clashed with London Mayor Sadiq Khan in a passionate debate at Wembley Arena.

The debate on Tuesday evening was a final opportunity for the two camps to win over voters, with polls showing an extremely tight race hours before a vote that will shape the future of Europe.

Brexit: Is the European Union still attractive?

Panellists locked horns over immigration, as the pro-EU London Mayor tore into his predecessor Boris Johnson, a key campaigner on the Leave side.

How much does the UK really pay the EU each week?

One of the most disputed campaign issues is the Leave camp's claim that the UK pays £350m - that's about $440m - to the European Union each week.

It says that money would be better spent on things such as Britain's squeezed universal healthcare system, the NHS. So, does the UK actually send millions to Brussels each week? Well it's a grey area that needs a lot more context.

The EU is funded by contributions from member states. Each week, Britain's contribution is about $440m. But, and here's where it gets tricky, a fair chunk of that money gets returned.

There's an instant rebate that shaves about $135m off. A further $115m is given back to spend on EU projects in Britain. It's used for things such as farming subsidies and stimulus programmes in poorer areas.

But the Leave campaign points out that the way that money is spent is largely decided by the EU, not Britain. What's left is a contribution of about $250m a week - almost half the original figure.

And the EU also gives about $40m to the UK's private sector each week, to fund things such as university research.

- Barbara Serra

"You're telling lies and you're scaring people," Khan declared as he brandished a Leave leaflet warning that Turkey could join the EU.

Johnson threw the criticism back at Khan, saying the pro-EU side had run a "Project Fear" by warning that leaving the 28-member bloc would damage Britain's economy.

The Conservative MP promised Britain an "independence day" on Thursday if it voted to leave, bringing sections of the audience to their feet in prolonged applause.

The prospect of Britain becoming the first state to defect from the EU in the bloc's 60-year history has raised fears of a domino-effect collapse of the European project.

European Commission President Jean-Claude Juncker flatly rejected suggestions that Britain might be able to negotiate better terms with the EU if it votes to leave. "Out is out," he said.

'Very hostile'

As the audience filed into the 12,500-seat Wembley Arena, which often hosts global music stars, they were serenaded by pro-Remain demonstrators singing "All You Need is Love".

Organisers Avaaz said the serenade was an attempt to counter the "fear and division" of the campaign.

But the two sides remained deeply opposed and the audience split among equally vocal Remain and Leave crowds.

Brexit Q&A: All you need to know

As the debate concluded, the Daily Mail newspaper announced that it was endorsing Brexit.

Is Brexit driven by the fear of migrants?

"Lies. Greedy elites. Or a great future outside a broken, dying Europe," read its front page. "If you believe in Britain vote Leave."

Two newspapers, the Daily Express and The Sun, carried front-page stories reporting that Queen Elizabeth II was challenging guests to give her "three good reasons" why Britain should stay in the EU.

Earlier this year, Buckingham Palace issued a rare complaint over a previous article by The Sun that claimed the queen favoured Brexit, a challenge to the monarch's long-held position of political neutrality.

The Times, which has backed Britain remaining in the EU, published a warning from hundreds of business leaders, including Virgin boss Richard Branson and US media mogul Michael Bloomberg, warning that Brexit could cause an "economic shock".

Deeply uncertain

The outcome looked deeply uncertain, as a poll by Survation gave Remain 45 percent and Leave 44 percent, with 11 percent undecided.

Ireland wary of EU Brexit

Six major bookmakers showed the odds heavily pointing to a Remain vote, with the likelihood of Britain staying in put at around 80 percent. The latest surveys were mostly conducted after the brutal murder of Jo Cox, a 41-year-old Labour politician who campaigned to remain in the EU, who was shot and stabbed in her northern English constituency on Thursday.

Her alleged killer, 52-year-old Thomas Mair, gave his name as "Death to traitors, freedom for Britain" at his first appearance in court after being charged with her murder.

In an interview with the BBC on Tuesday, Cox's widower Brendan said she had been "worried" the debate may have been "whipping up hatred".

A couple stand by the Thames near a Vote Remain projection on to the exterior of Tate Modern art gallery, in London [Dylan Martinez/Reuters]

Source: Al Jazeera and agencies