(Credit: TIMOTHY A. CLARY/AFP/Getty Images)

Hundreds of Occupy Wall Street supporters marched in New York City today to protest what they called the NYPD's "acts of brutality" against demonstrators and to demand the resignation of Police Commissioner Raymond Kelly in the wake of what they say were violent crackdowns on activists.

Protesters marched from Zucotti Park to Union Square, chanting, "The people united will never be defeated!"

"Former commissioner Raymond Kelly, we, the people have decided you no longer have a job. Any acts of brutality you order as we act only serve as further evidence of your misconduct," read a statement on the Occupy Wall Street website.

The statement claimed that last Saturday, police officers kicked, punched and beat OWS protesters during a peaceful "spring celebration." The demonstrators called today's march Let Freedom Spring, and said it was an effort to reclaim their right to celebrate spring without being the victims of police brutality.

"They have spied on us, they have assaulted us, they have kidnapped us from the streets without cause or charge. We, the 99% of people who will no longer be silent have chosen to make our voices heard," OWS wrote of the NYPD.

"The government of every major city where occupations have sprouted … monitor and target electronic communications and persecute, smash, chase away, beat, gas torture and deny rights to protesters," spokesman William Jesse told ABC News. "They beat thousands and thousands of Americans violently and illegally detain them while doing protected activities. Just like the beating and chasing of blacks in the '50s, police are tools used in a system to oppress Americans.

"The USA is hosting as many human rights abuses by our local and fed gives. And it's being ignored by main stream media and police because Americans are quiet sheep," Jesse said. "We need to continue rising."

Protesters to Gather at United Nations Headquarters

At 5 p.m., protesters gathered at the United Nations headquarters in New York in an effort to "expose how corporate influence has superseded strong action on climate and sustainable development in the international community," Jesse said.

To demonstrate corporations' hold on the United Nations' environmental goals, protesters plan to put on a form of street theater by dressing up in business attire to represent the "1 percent" - the richest Americans - and participating in a "mockupation" of the UN. Jesse said they are hoping to force the NYPD to take action against the "1 percent," at least in appearance.

Jeremy Brecher, the author of 10 books on labor and social movements, will speak at the event, which OWS said will launch the global " Disrupt Dirty Power" campaign.