New York: Police and protesters clashed in New York on the six-month anniversary of Occupy Wall Street when activists tried to reoccupy the park in New York's financial district where their movement was born.

Left-wing film maker Michael Moore joined about 600 people chanting "All day, all week, occupy Wall Street!" in Zuccotti Park on Saturday.

The rally, which began in the evening, grew bigger when reinforcements arrived, saying they were ready to stay on the square late into the night. Shortly before midnight, protesters erected a makeshift tent of cardboard and tarpaulin in contravention of rules banning shelters in the park.

Then police moved into the crowd and started to make arrests, sparking chaotic scenes as hundreds of other protesters tried to hold their ground.

Earlier in the day, protesters had marched on nearby Wall Street, resulting in another unspecified number of arrests, police said.

Zuccotti Park was the focal point of the OWS movement when it sprang up in September last year, but a tent camp maintained there by the mix of anti-capitalists, anarchists and people simply disillusioned with their economic future was evicted after two months.

Since the eviction, the movement, which at one point spawned similar tent camps in cities across the United States, has struggled to rally large numbers or find new ways to make its presence felt. However with warmer spring weather arriving, expectations are that Occupy leaders will try to regain their momentum.

Protesters seemed invigorated by their relatively large numbers compared to the small turnouts during street demonstrations over the winter. Some of their old chants were repeated and the former tent camp's famous to some, notorious noisy drum circle was up and running.

"New York is a people's town. Occupy, shut it down!" the crowd chanted, dancing at the same time.

Police watched quietly, but in large numbers from the sidelines. Earlier there were minor altercations when protesters marched through the narrow streets of the Wall Street neighbourhood.

"There was a peaceful march. There were some arrests, but we don't have a number yet," a police spokesman said.

Moore, the director of films including "Capitalism: a Love Story" and "Fahrenheit: 9/11," said he was "excited to see what will happen."

"We've never had anything like this in this country where we take on economic issues like this," he said.