Hundreds of activists have rallied in Washington to protest corporate greed and economic inequality, joining a movement than began in New York last month and has spread to several major U.S. cities.

The activists gathered Thursday in Washington's Freedom Plaza and marched to the White House, expressing a variety of demands, including economic reforms and an end to U.S. involvement in conflicts abroad. Some protesters planned to camp out in the plaza overnight.

The Washington activists echoed the demands of the “Occupy Wall Street” movement, which mobilized several thousand protesters in New York's financial district on Wednesday. The movement began on September 17 with small groups of demonstrators and has since grown with support from labor unions. Small anti-Wall Street protests also have taken place in other parts of the country.

Many of the protesters are angered by what they call the 1 percent of the U.S. population that monopolizes the country's power and wealth. A frequent chant heard at the anti-Wall Street rallies is “we are the 99 percent.”

U.S. President Barack Obama acknowledged the protests in a news conference Thursday, calling them a sign of the “frustration” that many Americans feel toward the financial establishment they blame for the recent global economic crisis.