OAKLAND -- The last time Occupy Oakland supporters tried to turn a vacant building into a base of operations, police moved in quickly.

Now as members of the movement prepare Saturday to once again take over an undisclosed vacant building and turn it into a social center, they're warning authorities not to interfere.

"If you try to evict us again, Occupy Oakland will make your lives more miserable than you make ours," said Occupy supporter Leo Ritz-Barr, reading from a letter that the movement was sending to city leaders, including Mayor Jean Quan and interim police Chief Howard Jordan.

Another eviction could result in a "permanent occupation" of the Port of Oakland, Oakland International Airport or City Hall, Occupy members said Wednesday during a news conference in Frank H. Ogawa Plaza. They also threatened to call on the activist hacker group Anonymous for support.

Occupy supporters refused to disclose the targeted building, saying only that it either has been foreclosed upon or is owned by a major corporation that is not putting it to good use. A discussion late last year on the group's website had contemplated occupying the unused Oakland Municipal Auditorium on 10th Street.

Occupiers are planning to gather at noon Saturday at Frank H. Ogawa Plaza and walk to the move-in site, where they intend to kick off the occupation with a two-day festival.

City officials declined to comment on the group's plans.

Police were not available to comment but have previously evicted Occupy supporters after requests from building owners.

Occupiers briefly took over the vacant Traveler's Aid Society building near the plaza late on Nov. 2. They announced plans to use it as a winter headquarters and community center, but police moved in and evicted them before the night was over.

John Most, a member of Occupy Oakland's Move-in Assembly, said the group had been planning the current action for weeks and was better organized this time around.

The building would house a kitchen, library, dormitory, school and event space -- and could hold general assemblies and other gatherings that still often take place outside City Hall.

"We're going to do our best to hold on to the space with moral force," Most said. "Our claim on it is legitimate. Our purposes are good, and they're to the benefit of a lot of people."

Contact Matthew Artz at 510-208-6435.