SAN FRANCISCO (Reuters) - Police cleared an "Occupy" protest in Oakland, California, early on Tuesday, breaking up an overnight camp at a plaza near city hall that has been the site of two weeks of demonstrations, a city spokeswoman said.

Oakland city spokeswoman Karen Boyd said she did not yet know how many of the protesters had been arrested in what the city described as an enforcement action at Frank Ogawa Plaza.

"We have contained the plaza, we are in the process of mobilizing the clean-up phase," Boyd said.

The city said in a statement it had told protesters last Thursday to cease overnight camping and cooking at the plaza. More warnings were issued on Friday and Monday. Daytime demonstrations will be permitted, the city said.

The city said it began to clear the plaza at about 4:30 a.m. local time and had "contained" the area in about an hour.

Businesses were asked to delay opening indefinitely on Tuesday, city employees were advised to delay their arrival at work as well, a nearby rail station was closed and buses rerouted temporarily, the city said.

Oakland city said in a statement that conditions at the plaza had begin to deteriorate by the second week with police, fire and medical care reporting they were denied access to the plaza to respond to service calls.

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

The protests focus on anger over government bailouts of big banks and persistent high unemployment, and have sprung up across the United States and in other countries.

Hundreds of demonstrators have been arrested in New York since the protests began. There have also been numerous arrests in other cities.

In the last week, Chicago police arrested about 130 protesters in Grant Park, the site of demonstrations during the 1968 Democratic convention in Chicago, and another 15 people at a protest in Philadelphia.

(Reporting by Emmett Berg; Additional reporting by David Bailey in Minneapolis; Editing by Jerry Norton)