Around 370 people have been occupying Oakland's  Frank Ogawa Plaza for the past two weeks  [Reuters]

Oakland police say they have arrested 85 people while clearing an anti-Wall Street protest in front of the City Hall that had grown into an encampment.

Protesters have been camping for two weeks at the Frank Ogawa Plaza, the site of two weeks of "Occupy Wall Street" protests in the centre of Oakland, California.

Most of the people arrested were taken into custody on suspicion of illegal lodging, a misdemeanour, as police raided the encampment early on Tuesday morning.

Karen Boyd, the Oakland police spokesperson, told Reuters news agency that "those arrested now face charges for camping or assembling without a permit".

Boyd said the Oakland police began to clear the plaza before dawn and had "contained" the area within an hour.

About 350 people were in the plaza when police began to clear the area by deploying beanbags and spraying tear gas at the protesters.

Boyd confirmed that there were no reports of injuries.

The protest was dubbed as the Oakland version of the 'Occupy Wall Street' movement launched more than a month ago in New York.

The protesters were campaigning against the government bailouts of big banks, high unemployment and economic inequality in the United States.

Demonstrations have spread across the nation and overseas, although crowds remain relatively small in most
cities.

Jean Quan, the Mayor of Oakland, said in a statement that she told protesters to cease overnight camping and cooking at the plaza.

"Over the last week it was apparent that neither the demonstrators nor the city could maintain safe or sanitary conditions, or control the ongoing vandalism," Quan said.
 
The Mayor's office said conditions at the plaza had begun to deteriorate by the second week of the protests with police,
fire and medical care reporting they were denied access to the plaza to respond to service calls.

Officials said the plaza was damaged by graffiti, litter and vandalism.

Hundreds of protesters in Oakland marched towards the City Hall several hours after the arrests.

The protesters took to the streets Tuesday evening after gathering at a downtown public library.

Police officers in riot gear met them en route and several small skirmishes broke out.