Thousands of people have seen in the New Year with spectacular fireworks displays in London, Edinburgh and across the UK.

More than 12,000 fireworks transformed the capital’s famous skyline as Big Ben struck midnight, watched by thousands of ticket holders packed along the River Thames under tight security.

The display ended with the Mayor's slogan "London is Open", angering some viewers who complained of the display being "politicised" in the wake of Brexit.

Auckland hosts fireworks spectacular as New Zealand welcomes 2017

More than 80,000 people also gathered in Edinburgh for the Scottish capital’s famous Hogmanay celebrations, watching concerts and dancing traditional ceilidhs.

Three fireworks displays were held leading up to the “midnight moment” spectacular from the ramparts of Edinburgh Castle.

Security fears failed to dampen the celebrations, which saw thousands of police deployed across the country amid fears of terror plots targeting crowds.

The Mayor of London, Sadiq Khan, said London had been made “as safe as it possibly can be” with measures including concrete barriers to prevent a Berlin and Nice-style lorry attack.

Describing the mood on the streets as “upbeat”, he said it was “really important we don't allow terrorists to disrupt our celebrations on this New Year's Eve”.

Fireworks light up the sky during the Hogmanay New Year celebrations in Edinburgh. (PA)

The Metropolitan Police said 20 people had been arrested at the celebrations but did not detail the offences.

In Edinburgh, thousands of party-goers joined hands for the world’s largest rendition of Auld Lang Syne at the stroke of midnight.

Cities including Cardiff, Belfast, Glasgow, Manchester, Birmingham, Newcastle and Nottingham held their own fireworks displays, with countless more being launched by families at their homes.

A driver fled the scene of a New Year's Eve crash that killed a 12-year-old girl and left another child fighting for her life in hospital, police have said.

As people prepared to see in 2017, a 12-year-old girl was killed in a hit and run crash in Oldham.

In pictures: World celebrates New Year's Eve 2016 Show all 16 1 /16 In pictures: World celebrates New Year's Eve 2016 In pictures: World celebrates New Year's Eve 2016 Fireworks explode over the Sydney Harbour Bridge and the Sydney Opera House on December 31, 2016 Getty Images In pictures: World celebrates New Year's Eve 2016 The SkyTower firework display during New Year's Eve celebrations on January 1, 2017 in Auckland, New Zealand. Getty Images In pictures: World celebrates New Year's Eve 2016 People release white balloons, carrying their wishes, to celebrate the New Year at Prince Park Tower in Tokyo On January 1, 2017. AFP/Getty Images In pictures: World celebrates New Year's Eve 2016 People attend the count down event to celebrate the arrival 2017 new year during New Year's Eve celebration at Beijing Olympic Park in China, 31 December 2016. EPA In pictures: World celebrates New Year's Eve 2016 New Year Eve's fireworks illuminate the Marina Bay in Singapore, 1 January 2017. EPA In pictures: World celebrates New Year's Eve 2016 South Koreans strike a bell during New Year celebrations in South Korea, 1 January 2017. EPA In pictures: World celebrates New Year's Eve 2016 Fireworks explode over Victoria harbour during New Year celebrations in Hong Kong on January 1, 2017. AFP/Getty Images In pictures: World celebrates New Year's Eve 2016 Fireworks explode over Moscow's Kremlin complex during New Year celebrations in Moscow on January 1, 2017. AFP/Getty Images In pictures: World celebrates New Year's Eve 2016 Fireworks explode above the pyramids during New Year's day celebrations on the outskirts of Cairo, Egypt, January 1, 2017. Reuters In pictures: World celebrates New Year's Eve 2016 Fireworks explode over the Al-Nusoor Square during the New Year celebrations in Baghdad, Iraq January 1, 2017. Reuters In pictures: World celebrates New Year's Eve 2016 Fireworks are seen above Pyongyang, North Korea, for New Year on January 1, 2017. Reuters In pictures: World celebrates New Year's Eve 2016 Fireworks explode at the Burj Khalifa, the world's tallest building, and surrounding skyscrapers to mark New Year in Dubai AP In pictures: World celebrates New Year's Eve 2016 Fireworks explode behind the Brandenburg Gate at midnight on January 1, 2017 in Berlin, Germany Getty Images In pictures: World celebrates New Year's Eve 2016 Revellers watch a fireworks show over the Arc de Triomphe monument, from the Champs-Elysees avenue as part of the New Year celebrations on January 1 , 2017 in Paris. AFP/Getty Images In pictures: World celebrates New Year's Eve 2016 Fireworks light up the London skyline and Big Ben just after midnight on January 1, 2017 Getty Images In pictures: World celebrates New Year's Eve 2016 Fireworks light up the sky during the Hogmanay New Year celebrations in Edinburgh. PA

An 11-year-old girl was also critically injured in the incident shortly after 7.15pm, Greater Manchester Police said.

The New Year had arrived a second later than normal because of a “leap second” needed in countries using Greenwich Mean Time to account for a slowdown in the earth’s rotation.

The UK’s festivities followed celebrations around the world, which started in New Zealand and Australia earlier on Saturday, followed by spectaculars in countries across the globe to see in 2017.

Germans defied terror fears to party on the streets of Berlin just weeks after an Isis supporter killed 12 people at a Christmas market.