Protesters launched worldwide street demonstrations Saturday against corporate greed and biting cutbacks in a rolling action targetting 951 cities in 82 countries.

Inspired by America's "Occupy Wall Street" and Spain's "Indignants", people took to the streets in Sydney, Hong Kong and Tokyo in the opening hours of the unprecedented global outcry.

It was the biggest show of power yet by a movement born on May 15 when a rally in Madrid's central square of Puerta del Sol sparked a protest that spread internationally.

Anger over unemployment and opposition to the financial elite hung over the protests, which coincided with a Paris meeting of G20 financial powers pre-occupied by the eurozone debt crisis.

But the demands and the sense of urgency among the activists varied depending on the city.

While hundreds protested in Asian cities, for example, up to 200,000 are reportedly expected in Rome where many are furious at Prime Minister Silvio Berlusconi's handling of a sovereign debt crisis.

Around 500 people gathered in the heart of Hong Kong's financial district to vent their anger at the inequities and excesses of free-market capitalism, while demonstrators in Tokyo also voiced fury at the Fukushima nuclear accident.

Wong Weng-chi, a demonstrator from a group calling themselves "Left 21", said the "Occupy Central" rally in Hong Kong was more than just an act of solidarity with the Wall Street protest, which began in September.

"Hong Kong is a key financial hub in Asia, it is a base that serves many multinational financial institutions. It is a base that serves many capitalists and the upper class to monopolise the wealth," he told AFP.

Hong Kong, a city of seven million people, is known for its super-rich tycoons, low taxes and teeming shopping districts.

Around 600 demonstrators in Sydney set up camp outside Australia's central bank, where the plight of refugees and Aboriginal Australians was added to the financial concerns.

In Tokyo, around 100 protesters marched through the streets, shouting "Occupy Tokyo!". They added anti-nuclear slogans as they passed the offices of Tokyo Electic Power Co, the operator of the stricken Fukushima plant.

Tomoko Horaguchi, a 22-year-old student at Hosei University, said she was moved by the protesters on Wall Street.

"I feel the same anger," Horaguchi said. "In particular I am angry at nuclear power plants. Only one percent of people want to run them still."

The organisers, relying heavily on Facebook and Twitter, say demonstrations will be held in 951 cities across 82 countries in Europe, North America, Latin America, Asia and Africa.

The "indignant" protests first took hold in Spain, which has a jobless rate of 20.89 percent rising to 46.1 percent for 16-24 year olds, where for a month activists lived in a ramshackle camp in Puerta del Sol.

They then spread to Europe, finding strong backing in crisis-hit countries like Greece, and then worldwide -- last month reaching the centre of global capitalism in Wall Street.

Since September 17 several hundred people have occupied a camp in a small park in the New York financial district.

The protesters declared victory Friday morning when New York authorities at the last minute postponed the evacuation of their camp.

An impromptu celebration march to nearby Wall Street ended in scuffles and 14 arrests when protesters ignored police instructions to remain on the sidewalks so as not to impede traffic.

US police arrested about three dozen other protesters in Denver, Seattle and San Diego.

Organisers called a rally in Times Square for 5:00pm (2100 GMT), saying they would be at the centre of the international protests.

In Madrid, five marches will converge on the city's emblematic square of Cibeles at 6:00 pm (1600 GMT) before proceeding to Puerta del Sol for assemblies lasting through the night.

In Italy, 70 buses are set to bring protesters from throughout the country to a demonstration in Rome which is set to get underway at 1200 GMT.

Over 100 authors, including Salman Rushdie and Pulitzer Prize-winning novelist Michael Cunningham, have signed an online petition declaring their support for the protests.