The world has begun celebrating the New Year, with revellers in Australia and New Zealand among the first to usher in 2016.

Crowds counted down the last seconds of 2015 at Auckland's Sky Tower in New Zealand at 1100 GMT, with a laser show and fireworks display.

Up to 25,000 people had been expected to turn up for the festivities.

In Australia, fireworks lit up Sydney harbour at midnight (13:00 GMT). A million were expected to turn up.

New Zealand welcomed in 2016 an hour after Samoa and Kiribati, the first countries to ring in the New Year.

As the New Year sweeps across Asia, major cities like Hong Kong, Singapore and Beijing will kick off their own celebrations.

In Egypt, festivities will be staged in front of the pyramids near Cairo, as the government works to revive its tourist industry.

Meanwhile, in Dubai, an extravagant display will illuminate the Burj Khalifa, the world's tallest building, with 400,000 LED lights and 1.6 tons of fireworks set to be used.

Fireworks explode over the Sydney Opera House in a 9pm display before the midnight fireworks which will usher in the new year in Australia's largest city, December 31, 2015. Photo: Reuters

When 2016 hits Europe, approximately one million people will countdown at the Brandenburg Gate in Germany's capital, Berlin.

Despite security fears across the continent, many major public events are going ahead, though with heightened security restrictions.

In Madrid, only 25,000 people will be allowed into the Puerta del Sol Square. More than 100,000 people are expected to watch the Mayor of London's fireworks show, a ticketed event.

Over in Sierra Leone, the declared end of Ebola will mark a return to festivities, after Freetown, the capital, was left deserted a year ago due to the disease's outbreak.

Fireworks explode over the Sydney Opera House in a 9pm display before the midnight fireworks which will usher in the new year in Australia's largest city, December 31, 2015. Photo: Reuters

As 2016 finally reaches the Americas, up to a million people are expected to converge on Times Square in New York, amid tight security, to watch the famous ball descend.

On Rio de Janeiro's Copacabana Beach, crowds will not only mark the New Year - they will also fete the 100th anniversary of Samba music, and the upcoming summer Olympics.