A demonstrator with Occupy Oakland blocks traffic near Frank Ogawa Plaza in Oakland, California. Police moved in early on Monday and dismantled the tent encampment on the plaza.

Oakland - Police moved in early on Monday and cleared out anti-Wall Street protesters from a plaza in Oakland, California, arresting 32 people but avoiding the sort of clashes that marked a previous attempt to shut down the Occupy Oakland camp.

Several dozen officers dressed in riot gear and carrying batons descended on the square shortly after dawn, but took a less aggressive approach than in a similar operation on October 25 and were met with less resistance from demonstrators.

On Monday, officers in some cases were smiling and talking with protesters as they took down more than 100 tents, under illumination from the searchlight of a helicopter hovering overhead. A separate line of officers kept a chanting crowd from entering the camp.

Before the camp was completely cleared, a crowd of protest supporters outside shouted “Shame on you!”

One watching protester, Joanne Warwick, said the police action was disturbing.

“Here we are after five weeks and we can't work this out,” she said.

In the October operation police and protesters clashed near downtown Oakland in one of the most violent episodes since the anti-Wall Street movement began in New York in September.

Former Marine Scott Olsen was critically injured during that altercation, giving impetus to the demonstrations across the United States. Olsen, 24, was released from the hospital last week and has called for peaceful demonstrations.

The Oakland group has been among the most visible and active in the Occupy movement, which has mobilised protesters who object, among other things, to a financial system they say only benefits the rich. One major protest temporarily shut down the Northern California city's port earlier this month.

By morning rush hour on Monday, the City Hall plaza was closed off by fences. Collapsed tents and debris lay scattered throughout the plaza.

Police and a handful of protesters lingered on the edge, the latter singing songs at an intersection blocked off by police as commuters rushed by to work.

“We had to bring the camps to an end before more people got hurt,” Mayor Jean Quan told a news conference after the action. City officials said they hoped to reopen the central plaza to demonstrators by 6pm PST (02h00 GMT on Tuesday) but would not allow camping.

“There will be a strong police presence at the plaza 24/7,” Acting Police Chief Howard Jordan said.

Occupy Oakland scheduled an afternoon meeting at the main downtown library, a different location than the plaza where protests have centred.

The city of Oakland had put out a notice addressed to “Dear Business Leader” on Monday morning, saying the police were enforcing an order issued on Friday.

It said “the City could not assure adequate public health and safety in the plaza” the protesters occupied, and suggested businesses might want to consider delaying the start of their work days on Monday.

The Oakland operation was one of several in recent days aimed at clearing protesters out of encampments authorities say have become dangers to public health or sources of crime.

The weekend saw police operations in Salt Lake City, Denver, and Portland, Oregon, as well as threats of action in other cities if protesters did not clear out on their own.

In St Louis, where 27 anti-Wall Street protesters were arrested on Saturday, attorneys for members of Occupy St Louis planned to take their battle to regain their downtown campsite to federal court on Tuesday.

They seek an injunction that would allow an overnight presence in Kiener Plaza, the downtown city park near the Gateway Arch where they maintained a camp for six weeks. - Reuters