London: Millions of enthusiastic voters flocked to polling stations across the UK on Thursday for the country's first December election in nearly a century to determine the fate of Brexit - Britain's impending divorce from the European Union.

British Prime Minister Boris Johnson and Opposition Leader Jeremy Corbyn were among the first to cast their ballots in London in an election that offers the electorate a stark choice between the Conservatives' pledge to leave the European Union (EU) on a signed withdrawal agreement and Labour's commitment to offer another referendum on the country's future relationship with the 28-member economic bloc.

Polling stations across all constituencies of the United Kingdom England, Wales, Scotland and Northern Ireland opened at 07:00 GMT where a total of 3,322 candidates are standing for election to 650 seats in the House of Commons.

The snap election had been called by Johnson in a bid to win a majority for his Conservative Party and get his Brexit deal through Parliament. The UK is due to leave the EU but has failed to find parliamentary consensus on the terms of that exit, missing repeated deadlines - the last one being on October 31.

While Johnson has been keen to characterise this as a Brexit election with the party's Get Brexit Done message with the new January 31, 2020 deadline in sight, the Opposition Labour Party and others have been focussed on highlighting his Tory government's failures across domestic issues such as the state-funded National Health Service (NHS).

Johnson, 55, cast his vote at a central London polling station, taking his dog Dilyn along with him.

Labour leader Jeremy Corbyn, Liberal Democrat leader Jo Swinson, Scottish National Party (SNP) leader Nicola Sturgeon, Green Party co-leader Jonathan Bartley and Wales' Plaid Cymru leader Adam Price all cast their votes. Brexit Party leader Nigel Farage said he has already cast his ballot by postal vote.

Under election day broadcast norms, it is expected for all parties to refrain from projecting party political analysis and a reference to opinion poll results is also kept at bay until the first exit poll result is declared at 22:00 GMT as soon as polling stations close.

The counting begins straight away, with Newcastle Central and Sunderland South and Houghton in the northeast of England holding the crown for the fastest to declare.

The results from most of the other constituencies are expected to be declared by the early hours of Friday, by which time the final tally becomes clear. Any party with more than half the MPs (326) in the Commons usually forms the government.

If no party has a majority of MPs, the one with the most can form a coalition, with one or more other parties to gain control.

The last YouGov poll to be released on the eve of the election on Wednesday showed Johnson holding on to his lead but kept the prospect of a hung Parliament within reach as well.

Despite a dreary, cold and wet weather, long queues were reported outside many polling stations, as initial turnout appeared to be brisk after a closely fought campaign billed by the Conservatives and the Labour as the "most important in a generation".

Many voters took to social media to say that polling stations were busier than usual today, after having to queue to cast their ballots.

"Never thought I'd see a queue like this outside my local polling station! I've barely seen more than about two other people there in the past," Karli Watson, a voter, tweeted.

Bryony Thomas in south London tweeted that there was a 20-minute wait to cast ballots at her polling station.

Elections in the UK traditionally take place every five years. But, in October, MPs voted for the second snap poll in as many years, resulting in the first winter election since 1974 and the first to take place in December since 1923.

Anyone aged 18 or over is eligible to vote, as long as they are a British citizen or qualifying citizen of the Commonwealth or Republic of Ireland and have registered to vote.

Many people have already put a cross next to the name of their favoured candidate by voting by post more than 7 million people of an estimated 46-million voting base used a postal vote two years ago.

The last election in 2017 had thrown up 12 Indian-origin MPs, including the first female Sikh MP Preet Kaur Gill and the first turbaned Sikh MP Tanmanjeet Singh Dhesi - both for the Opposition Labour Party.

Thursday's election looks set for a hike on that number, with Labour's Navendru Mishra and Conservatives' Gagan Mohindra and Goan-origin Claire Coutinho among the frontrunners to clinch their party's strongholds.

The ethnic minority surge in the number of MPs is expected to include all the Indian-origin MPs from the last election, except Labour's Keith Vaz - who announced his resignation just ahead of the election in the wake of a sex scandal.

For the Tories, Priti Patel, Alok Sharma, Rishi Sunak, Shailesh Vara and Suella Braverman are set for a return. For the Labour Party, besides Gill and Dhesi, the others contesting so-called safe seats include Keith Vaz's sister Valerie Vaz, Lisa Nandy, Seema Malhotra and Virendra Sharma.