Fireworks flash over Sydney Harbour during New Year's Eve celebrations. (Rick Rycroft/Associated Press)

Cities around the world heralded the arrival of the new year with kaleidoscopic fireworks, balloons, music and spectacular light shows.

In Australia, the skies lit up over Sydney Harbour as 1.5 million revellers took part in one of the world's biggest New Year's Eve parties and welcomed in 2010.

About 5,000 kilograms of pyrotechnics were set off during a 12-minute show as a final countdown ushered in the new year. In Auckland, about 700 kilograms of fireworks exploded from the city's Sky Tower.

People release balloons at the Zojo-ji Buddhist temple in Tokyo. (Kim Kyung Hoon/Reuters)

Millions of Japanese welcomed the new year by flocking to shrines to pray for good fortune in 2010. During the midnight countdown at the Zojo-ji Buddhist temple in Tokyo, celebrants released clear balloons, which floated through the air like champagne bubbles.

In the Philippines, officials say about 230 people were hurt by firecrackers and celebratory gunfire despite a government campaign warning people to take precautions and threatening violators of safety rules with arrest. Many Filipinos, largely influenced by Chinese tradition, believe that noisy New Year's celebrations drive away evil and misfortune.

China uses a different calendar that will mark the new year in February. Nevertheless, President Hu Jintao wished viewers a happy new year in an end-of-the-year speech broadcast on China Central Television. At an outdoor event in Beijing's World Trade Plaza Square, throngs of people released red, yellow, and blue balloons at midnight.

Crowds gathered at an outdoor event in Beijing and sent balloons into the sky. (Christina Hu/Reuters)

Crowds near the Taipei 101 Tower in Taiwan, one of the tallest buildings in the world, watched as shimmering fireworks exploded from the 508-metre skyscraper.

Islamic nations such as Pakistan and Afghanistan also use a different calendar.

The Eiffel Tower is jazzed up with a multicoloured, disco-style light display for New Year's Eve celebrations in Paris. (Michel Euler/Associated Press)Firecrackers were already exploding across the Netherlands early Thursday on the only day of the year the Dutch are allowed to set off fireworks.

In Paris, the Eiffel Tower was decked out for its 120th-anniversary year with hundreds of multicoloured lights along its latticework, showering the Iron Lady in a light show billed as more energy-saving than its usual sparkling lights.

Police blocked off the Champs-Elysées to vehicle traffic as partygoers popped champagne and exchanged la bise — the traditional French cheek-to-cheek peck — to celebrate the New Year.

In London, thousands braved frigid temperatures to gather along the River Thames for fireworks that were fired from the London Eye attraction just as Big Ben struck midnight — an hour after continental western Europe.

In New York City, hundreds of thousands of revelers gathered in chilly weather in Times Square to usher in the new decade. About 1,360 kilograms of confetti was scattered over the crowd when the New Year's Eve crystal ball dropped at midnight.

The celebrations brought out heightened police security, with thousands of police officers scattered around Times Square, some heavily armed, and revelers were banned from carrying backpacks and open bottles.

New York City's New Year's Eve celebrations brought out heightened police security around Times Square. (Tina Fineberg/Associated Press)Authorities also carried out sweeps to detect traces of radiation or biological agents in the area.

In Toronto, thousands of people packed Nathan Phillips Square in front of City Hall where musical groups entertained them in a show that began at 10 p.m. and was capped off by a fireworks display.

Subway and most bus and streetcar service was extended until 4 a.m., with people able to ride for free after midnight.

Economy, security dampen mood

The mood of celebrations was tempered in some places by the effects of the financial downturn, which bit hard in 2009, sending economies into recession, causing millions to lose their jobs and dramatically increasing the number of home foreclosures in some countries.

There were also reminders of the fight against terrorism, which during the decade led to wars in Iraq and Afghanistan and rising militant violence in Pakistan.

The U.S. Embassy in Indonesia warned of a possible terrorist attack on the resort island of Bali on New Year's Eve, citing information from the island's governor — although local security officials said Thursday they were unaware of a threat.

The advisory to U.S. citizens said counterterrorism efforts in Indonesia, a predominantly Muslim country, have been partly successful in recent years but violent extremists continue to pose a deadly threat.

With files from The Associated Press