Washington, Dec 13 (IANS): Police in several US cities confronted Occupy protests aimed and shutting down port facilities as part of a nationwide day of protest in the aftermath of efforts to clear demonstrators against corporate greed from public parks.

Several arrests were made, while ports reported only minor hindrances Monday in protest against efforts by cities across the country -- including New York, Boston and Oakland -- to clear the Occupy Wall Street protestors, CNN reported.

The Occupy movement which began Sep 17 in Zuccotti Park, located in New York City's Wall Street financial district, has since spread to over 70 major US cities, including Washington, where protesters have set up encampments in two public squares near the White House.

The protesters' slogan "We are the 99 percent" refers to the growing wealth disparity in the US between the wealthiest 1 percent and the rest of the population and targets corporate greed.

Police in Houston arrested 20 protesters after dozens of police on foot and on horseback confronted a somewhat larger group of Occupy protesters, who blocked an interstate on-ramp, authorities said.

Elsewhere, protesters affiliated with the nationwide "Occupy" movement set out in the pre-dawn hours in Oakland, California; Los Angeles and Portland, Oregon, to shut down ports in an effort to "disrupt the economic machine that benefits the wealthiest individuals and corporations," according to organizers.

About 80 protesters demonstrated outside the gate of San Diego's port, but caused no disruption, port spokesman Ron Powell said.

Protesters were planning a second occupation of the Oakland port Monday afternoon. Protesters in Seattle also were preparing to protest at the port there, according to organizing websites and posts on Twitter.

In addition to the West Coast port blockades, demonstrators in Salt Lake City and Denver said they were planning to disrupt operations of Walmart distribution facilities. About 40 to 50 people protested at the Denver facility, CNN reported.