DOWNTOWN — Police Commissioner Ray Kelly said Wednesday that the department could not bar protesters from Zuccotti Park since it is a public plaza that is required to stay open 24 hours a day.

"In building this plaza, there was an agreement it be open 24 hours a day," Kelly said of the park near the World Trade Center, which is owned by Brookfield Office Properties but operates as a public space.

"The owners have put out regulations [about what's allowed in park]. The owners will have to come in and direct people not to do certain things."

Kelly said the plaza, which is sandwiched between Broadway and Trinity Place at Liberty Street, acts as a thoroughfare for pedestrians.

A Brookfield spokeswoman said the company was worried about the protesters, but would not say whether they have asked the NYPD to remove them or take some other course of action.

"Zuccotti Park is intended for the use and enjoyment of the general public for passive recreation," said Melissa Coley, vice president of investor relations and communications for Brookfield, in a statement.

"We are extremely concerned with the conditions that have been created by those currently occupying the park and are actively working with the City of New York to address these conditions and restore the park to its intended purpose."

But the NYPD does not have the power to remove the protesters unless they're breaking the law or park regulations.

While hundreds of demonstrators continue to camp out in the plaza, some sleeping on mattresses and in makeshift tents, famous activists including Susan Sarandon, Cornel West and Michael Moore have come to visit them.

The protesters have been careful to keep the plaza clean, setting up a recycling center and taking turns sweeping the area.

Some lower Manhattan residents, though, have also started to complain about noise coming from the demonstrators.

A few of those staying in the plaza said Tuesday night they were not sure how long they would be there.

With cold weather fast approaching, several protesters said they didn't think they could stay indefinitely and may relocate to other cities where public places are being occupied.