Portland police warned on Friday that anti-Wall Street protesters in the city were fashioning makeshift weapons with wood and nails, in advance of a planned move by authorities to clear their two encampments over the weekend.

The statement from Portland police came a day after Portland Mayor Sam Adams, citing sanitation and safety concerns, gave demonstrators until 12:01 a.m. on Sunday to clear out their tents.

Demonstrators said this week they number between 500 and 800, and police confirmed the group numbers in the hundreds.

Police said the Occupy Portland demonstration, which has seen protesters camp out in two downtown parks, has been peaceful since it began over one month ago.

We are committed to it remaining peaceful but very concerned about information that people are massing for and preparing for a confrontation, police said in a statement.

Details on possible plans for violence within the camps come from people inside the encampments who are concerned, Portland police Sergeant Pete Simpson said.

There are reports weapons are being made with wood and nails, that a hole is being dug in one of the parks and that pallets are being turned into shields, said police.

There are also concerns that demonstrators could climb trees during an eviction. Removing people from trees presents unique challenges, Simpson said.

In reaction to the police warning, activists involved with Occupy Portland put out their own statement denying any plans for violence.

The Portland Police have been engaging for the last several weeks in a campaign to defame and confuse the message of our movement by attributing the actions and statements of individuals to the movement as a whole, and they continue to do so, the activists' statement said.

Occupy Portland activist Adriane, who declined to give her last name, also disputed the information from police.

I don't know anyone that is going to engage in violent behavior, she said.

But protesters are preparing for the possibility of being tear gassed by police and obtaining gas masks, she said.

Aside from the two downtown parks, the protest has also spilled over to a plaza owned by the federal government, and that camp will be included in the law enforcement action to clear out the encampments, Mayor Adams said this week.

Occupy Portland has emerged as one of several West Coast hubs of a nationwide campaign launched in September against what demonstrators describe as economic inequality, corporate excesses, high unemployment and bailouts of major banks.

The plan by Portland officials to close down the city's two protest camps is the latest by a major U.S. city aimed at closing similar sites that have sprung up across the country.

Clashes with police already have erupted in some other cities that have tried to remove camps of anti-Wall Street demonstrators, notably in Oakland, California, across the bay from San Francisco.

Occupy Portland activists are planning a family-friendly potluck dinner and march on Saturday at 5 p.m.

We need to spread calm and remain peaceful, Adriane said.