A few motorists beeped their horns, presumably in support, as they drove past a small gathering outside the William S. Moorhead Federal Building at lunchtime yesterday on Grant Street.

Others may have wondered what they were looking at.

About a dozen people -- some dressed in trench coats and dark glasses, some carrying homemade binoculars and even a telescope -- stood in front of the building for what they called a "spy-in."

It was organized by the Thomas Merton Center Anti-War Committee and Pittsburgh Bill of Rights Defense Campaign to bring awareness to recent instances of what they call government spying on local peace groups.

Last week, representatives of the Merton Center and the American Civil Liberties Union of Pennsylvania announced that they had documents that proved the FBI was spying on local peace activists.

Through a federal Freedom of Information Act request, the groups received 11 pages of records that revealed that an FBI agent watched and took photographs as members of the center passed out leaflets in November 2002 in Market Square.

The FBI denied it was conducting surveillance on the group, and instead said an agent was investigating one specific person.

At yesterday's spy-in, protesters carried signs that said: "Big Brother is Watching," "We're here for your protection," and "The FBI spying on peace activists is outrageous."

"The government's wasting money investigating pacifists," said Marty B. O'Malley, a Forest Hills councilman and Merton Center member.

On Saturday, he and more than 1,000 others participated in a three-mile march to protest the war in Iraq.

During that march, Mr. O'Malley said he saw dozens of police officers dressed in riot gear. He and others, like David Meieran, a volunteer with the Merton Center, objected to the large number of officers on hand for the march.

"The picture here is a very chilling one," Mr. Meieran said. "It felt like an effort to intimidate and put a chill on our First Amendment rights to dissent."

Pittsburgh Police Chief Dominic Costa said in an e-mailed response to questions yesterday that there was an adequate number of officers "based on the size and scope of the event."

"Were we expecting problems? No. Were we prepared in the event there were issues to deal with? Yes," Chief Costa wrote. "Preparation was necessary for the safety of the participants, the officers, residents and businesses/property in the area."

There were six police agencies involved in Saturday's march and rally. The Pittsburgh officers who worked were all on duty, Chief Costa said, and the city incurred $700 in overtime costs.