|Newly joined by labour unions, protesters will march from Foley Square to Zuccotti Park in New York [Reuters]
A diverse group of powerful unions has joined demonstrations in New York's financial district, lending institutional support, public credibility and potentially thousands of participants to a movement that began with a few university students.
The "Occupy Wall Street" protest movement, which began three weeks ago in New York's financial hub, was joined on Wednesday by a dozen US labour unions.
Among those who joined the clamour were members of the Chinatown Tenants Union and the Transit Workers Union, the liberal group MoveOn.org, and community organisations such as the Working Families Party and United NY.
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The groups will embark on a march starting at Foley Square in lower Manhattan, an area encircled by courthouses.
Organisers say the marchers will then head to Zuccotti Park, the unofficial headquarters where protesters have been camped out in sleeping bags. It is unclear how many people will be joining the march, but some organisers said thousands could show up.
"We're really excited that labour is part of the protest,'' said Sara Niccoli, a spokeswoman for the Labour-Religion Coalition, an Albany, New York-based organisation that aims to "do justice" for workers.
Al Jazeera's Cath Turner, reporting from the scene of the rally, said protest organisers are "ecstatic that more groups are starting to take hold" of the movement.
The organisers feel their reach and appeal is expanding, she said.
Getting more organised
Police said that United NY had sought a permit for the rally on Wednesday and were expecting about 2,000 people to attend.
"I think they're capturing a feel of disempowerment, feeling like nobody is listening to them," said Camille Rivera, executive director of United NY.
"What do you do when no one is listening to you? You speak up, you take action."
Occupy Wall Street movement turns online for help
Participants will not need permits to protest in a city in which picket lines and marches go on nearly every day. But a permit allows demonstrators to do things that would normally be illegal - like filling an entire street.
About 700 members of the Wall Street group were arrested and given disorderly conduct summonses for spilling into the roadway of the Brooklyn Bridge on Saturday despite warnings from police.
Paul Browne, a spokesman for the New York police department, said police were prepared for a large group march on Wednesday, and that officers were anticipating spillover onto the streets.
"Officers will be in the lane next to the sidewalk, and we will try to keep people on the sidewalk, but we realise they may need to walk on the street if it's crowded," he said.
The type of activity that could result in arrest would be if members of the group purposefully try to stop traffic on Broadway, Browne said.
The Occupy Wall Street protests started on September 17 with a few dozen demonstrators who tried to pitch tents in front of the New York Stock Exchange.
Since then, hundreds have set up camp in a park nearby and have become increasingly organised, lining up medical aid and legal help and printing their own newspaper, the Occupied Wall Street Journal.
Other groups have periodically gathered and protested in spots throughout the country.