Police wearing helmets and carrying shields evicted protesters with the Occupy Wall Street movement early morning from the park in New York's financial district where they have camped since September, dismantling their tent city and arresting 70 people.

Authorities declared that the continued occupation of Zuccotti Park - which had become a sea of tents, tarps and protest signs with hundreds of demonstrators sleeping there - posed a health and safety threat.

Police spokesman Paul Browne said that about 70 protesters were arrested in the park during the nighttime operation for defying orders to leave and several more were arrested nearby, although most left voluntarily.

About a dozen protesters had chained themselves together and another two had chained themselves to trees before being cut loose and removed, Browne added.

New York City Mayor Michael Bloomberg defended the move to evict the protesters and tear down their tent city.

'Unfortunately, the park was becoming a place where people came not to protest, but rather to break laws, and in some cases, to harm others.

There have been reports of businesses being threatened and complaints about noise and unsanitary conditions that have seriously impacted the quality of life for residents and businesses in this now-thriving neighborhood,' Bloomberg said in a statement.

The protesters had set up camp in Zuccotti Park on September 17 to protest a financial system they say mostly benefits corporations and the wealthy. Their movement has inspired similar protests against economic inequality in other cities, and in some cases have led to violent clashes with police.

The mayor said protesters and the general public can return once the park is cleaned, but would have to abide by rules banning items like tents, tarps and sleeping bags.

'Protesters have had two months to occupy the park with tents and sleeping bags. Now they will have to occupy the space with the power of their arguments,' Bloomberg said.

Protesters vowed that the eviction from the park that had become the epicenter of their movement would not deter them and several hundred congregated at another lower Manhattan square.

Police barricaded streets around the park, which had been lit up with spotlights. The operation began at around 1 am (0600 GMT) and the last protesters had been evicted by about 4:15 am. (0915 GMT).

Authorities swept up and removed mounds of debris. Police used a loudspeaker to tell protesters they would be arrested if they did not leave.

'They gave us about 20 minutes to get our things together,' protester Sam Wood said as the eviction was taking place. 'It's a painful process to watch, they are sweeping through the park.'

Browne said the city and the owners of the park, commercial real estate corporation Brookfield Office Properties, issued fliers to the protesters saying the park would be cleared for cleaning shortly after 1 a.m. (0600 GMT).

'The sanitation department is removing all their stuff,' Browne said, adding that protesters could collect belongings later in the day at another location in the city.

He said police would remain at the park to ensure protesters did not return with their belongings.

The flier said the city and Brookfield had decided 'that the continued occupation of Zuccotti Park posed an increasing health and safety hazard to those camped in the park, the city's first responders and the surrounding community.'

The protesters had set up a kitchen in the middle of the park and they also had a medical tent, a social media headquarters and a library. Protesters have said several hundred people had been regularly sleeping in the park.

Authorities had previously threatened to clear the park but backed down. On October 14, plans to clean out Zuccotti Park were postponed, averting a possible showdown between police and protesters.

Occupy Wall Street supporters said the eviction would not crush their movement. 'It will only grow stronger now. Why? Because every single person who was forced out of the park will bring five friends and everyone who heard about it will bring themselves and their friends,' said Justin Wedes, 25.

'After this we get bigger. There is no question we get bigger. This is our chance to be heard,' added Jennifer Sarja, 38, who had been bringing blankets and food to protesters staying in the park.

Wood, an unemployed 21-year-old from Farmingdale, New York, said he had been living at the park since the protests started on Sept. 17.

'They weren't disassembling anything nicely. ...They trashed our library,' Wood said.

Some people applauded the action taken by authorities. 'I'm glad they cleared the park,' said Patrick Hickey, 45, who works in construction at the nearby World Trade Center site.

'I think the point they were trying to make was made a long time ago and it got lost along the way,' he said as he had a cup of coffee and watched the park being cleaned.

Police on Monday moved into an encampment by anti-Wall Street protesters in Oakland, California, clearing out occupants and taking down tents, while in Portland, Oregon, police confronted an estimated 1,000 protesters on Sunday.-Reuters