Baton-wielding riot police scuffled with hundreds of demonstrators protesting the U.S. military presence in Central America and arrested about 275 people at federal buildings in San Francisco and Minneapolis.

Meanwhile, in Spokane, Wash., supporters of continued aid to the Nicaraguan Contras waved signs that read, "Contras Yes, Commies No" and "Stop The Russians Before They Reach Our Borders." About 150 people on opposite sides of the issue gathered for peaceful rallies in front of the federal courthouse.In San Francisco, a yelling, sign-toting crowd of more than 500 people encircled the Federal Building early Monday. Helmeted police arrested 225 people.

Shortly after the protest began at 7 a.m. Monday, San Francisco police began making arrests for blocking entrances and the streets around the 20-story building. The main entrance was closed, and for about a half-hour the protesters blocked the rear entrance that police were trying to keep open.

More than 5,000 people work in the building.

Some demonstrators held aloft a 6-foot-long sign reading, "This building closed for renovation of morals." Many held signs insulting to President Reagan and shouted obscenities.

Protesters shouted "No Contra aid" and "U.S., CIA, out of Nicaragua," as they marched in a ragged oval in front of the closed main entrance, while early arrivals for work got in through the back doors.

At one point, screaming protesters swarmed against a lawyer trying to get in. Police fought the demonstrators aside and pulled the man through.

Officers with visored helmets and batons marched on the double from one street to another as protesters harassed them with quick moves. Some protesters went limp and were dragged screaming to the police vans.

A man in his early 20s who didn't move fast enough for charging police was hit in the mouth with a baton and bloodied.

The demonstators were photographed and booked on the street before being taken to the Hall of Justice for formal citations.

Police, moving in with batons chest-high, began rounding up demonstrators after police Capt. William Welch warned the hooting crowd through a loudspeaker that they were illegally assembled and ordered them to disperse. Some were charged with resisting arrest.

In Minneapolis, riot police arrested about 50 protesters Monday after they marched through downtown to the Federal Building, broke a window and threw paint.

Officers used 4-foot-long sticks to keep the crowd under control, arrested demonstrators and dragged those who wouldn't go peacefully to police vans.