Media playback is unsupported on your device Media caption Watch how London celebrated the start of 2020

Revellers across the UK have rung in the start of a new decade, with fireworks displays in London, Edinburgh and other major cities.

In London, some 12,000 fireworks lit up the capital's skyline.

Edinburgh hosted what it promised would be the UK's "biggest street party" as part of the city's Hogmanay celebrations.

Firework shows were also held in other cities including Manchester, Cardiff, Newcastle, Inverness and Nottingham.

Prime Minister Boris Johnson, in his new year message, said the UK was on the verge of a "new chapter" in its history and promised to "finish the job" by delivering Brexit within weeks.

He said he hoped the country would "move forward united" after it leaves the EU on 31 January.

Meanwhile, the Archbishop of Canterbury used his message to suggest that Britons should make a "heroic new year's resolution" to contact someone they have drifted apart from.

Image copyright Getty Images Image caption An explosion of colour lit the sky by Westminster Abbey

Image copyright Reuters Image caption The display - over the River Thames - was promised to be the best the capital had "ever seen" by London Mayor Sadiq Khan

Image copyright PA Media Image caption The London Mayor said the fireworks celebrated the capital as a "global city" and a "European city"

Image copyright Reuters Image caption Partygoers lined the Thames and boarded boats for a view of the display

Image copyright Reuters Image caption Some 100,000 revellers packed into the areas around the Victoria Embankment

In London, Big Ben's chimes sounded the start of the display, despite them being silent this year while renovation work is completed.

Around 100,000 revellers packed into the streets around Victoria Embankment as the roar of football anthems such as Three Lions kicked off the new decade, with the festivities providing a prelude to the Euro 2020 football tournament.

Music from artists including Stormzy, Wiley and Bastille also featured in a display London Mayor Sadiq Khan said would be the best the capital "has ever seen".

"We may be leaving the European Union, but we're not leaving Europe. So tonight's fireworks celebrate us as a global city, us as a European city," he added.

He stressed that London and the UK need to be brought "together again" in the 2020s.

"I'm not pretending that fireworks and one night can do that, but I think it's really important [that] we celebrate, tonight, some great things about our city and our country," he said.

On social media, some praised the spectacular display while others complained that a build-up of smoke obscured the view.

The Metropolitan Police said there were 15 arrests at the celebrations in central London, including two arrests for offences involving fireworks and one for sexual assault.

In Edinburgh, more than 3,600 fireworks were let off from the castle as the Scottish capital celebrated Hogmanay.

Image copyright PA Media Image caption In Edinburgh, street parties have been taking place to celebrate Hogmanay

Image copyright PA Media Image caption The city's famous castle was the focal point for the fireworks display

Image copyright PA Media Image caption The Scottish capital was packed with people seeing in the new year and new decade

Musical artists including DJ Mark Ronson, Idlewild, Rudimental and Marc Almond performed on stages throughout the city centre.

Tens of thousands of people attended the party, which extended across more than a dozen streets in the city.

The Scottish Ambulance Service said it had an "exceptionally busy" Hogmanay across the nation, with more than 2,500 calls in the 12 hours from 19:00 GMT on 31 December.

Media playback is unsupported on your device Media caption New Year Fireworks: The world welcomes 2020

The first places to welcome 2020 included the tiny Pacific island of Kiribati, neighbouring parts of Samoa and the Chatham Islands.

Auckland in New Zealand was the first major city to ring in the new decade, with thousands welcoming 2020 at a fireworks display at the city's Sky Tower.

The traditional fireworks display in Sydney Harbour also went ahead, despite calls for it to be cancelled due to Australia's bushfire crisis.

European cities, including Paris, Berlin, Madrid and Athens, have also seen in the new year with firework displays.

The uninhabited Baker Island and Howland Island, on the other side of the International Date Line, were the last to leave 2019 behind.