Dozens of people were arrested Saturday as police on horseback clashed with anti-corporate greed protesters in New York's famous Times Square during a global day of "outrage" against corporate greed.

"Occupy Wall Street" protesters were taken away in police vans after marching uptown, while thousands of people converged on the major commercial intersection, divided by police barriers.

The clashes took place at the corner of 46th Street and Seventh Avenue amid a heavy police presence after day-long marches that began in the Financial District. Rowdy demonstrations also unfolded in dozens of countries.

Mounted police pushed back protesters who were trying to enter Times Square. Dozens of panicked people then began to run and a woman fell down. She had face injuries and was swiftly carried away on a stretcher.

Police arrested 24 other protesters earlier for trespassing at a Citibank branch, a New York Police Department spokesman said. Demonstrators also walked to Chase Bank in support of the 14,000 workers sacked by the lender in the wake of cutbacks made after a government bailout totaling $94.7 billion.

Students, families with strollers and trade unionists, watched by a large police presence, marched towards Wall Street carrying placards, chanting: "We are the 99 percent," "We are the people" and "Mr Obama we need your support."

Families joined the march and several open-top buses filled with tourists cheered on the protesters by making the V for victory sign.

Citibank said its branch staff had called police after a "large amount of protesters" entered the bank near Washington Square Park.

"They were very disruptive and refused to leave after being repeatedly asked," Citibank said in a statement. "The police asked the branch staff to close the branch until the protesters could be removed."

It said only one person had asked to close an account, and was granted that request.

The Occupy Wall Street movement was buoyed by a decision Friday to halt plans to kick them out of the New York park they have called home for a month.

In Washington, between 2,000-3,000 people assembled at the National Mall on the eve of the inauguration of a memorial to slain Nobel peace laureate Martin Luther King Jr.

"We have bailed out the auto industry, and we should have. We bailed out Wall Street. Now it's time to bail out working Americans. That's what this is about," the civil rights leader's son Martin Luther King III told the crowd.

"I believe that if my father was alive, he would be right here with all of us involved in this demonstration today."

The Reverend Al Sharpton, a fiery civic activist, chimed in: "Occupy Wall Street, occupy Washington, occupy Alabama! We've come to take our country back to the people." The reference to Alabama was over a recent strict anti-illegal immigrant law that has been slammed by rights activists.

Around 200 demonstrators in the US capital had earlier marched to a Bank of America branch, where they had planned to close accounts. But they were not allowed inside and the bank was hastily closed.

In Miami, a city that rarely hosts mass demonstrations, at least 1,000 people marched downtown. The crowd included youth and retirees standing up against corporations, banks and war. No police could be seen as the group approached government buildings.

Hollywood actor Sean Penn became the latest celebrity to offer his backing to Occupy Wall Street, a group of demonstrators who on September 17 took up residence in New York's Zuccotti Park and began their ongoing campaign that has since seen related protests sweep the globe.

"I applaud the spirit of what is happening now on Wall Street," Penn told interviewer Piers Morgan on CNN late Friday.

"This generation - and this does begin, I think significantly with the Arab Spring - is starting to tell the world that we cannot be controlled by fear any more and we will not be denied."