On Monday, the New York Police Department sent its warrant squads after an unusual set of suspects: people who had old warrants for the lowliest of violations, misconduct too minor, usually, to draw the attention of those squads.

But those who were questioned by the warrant squads said the officers had an ulterior motive: gathering intelligence on the Occupy Wall Street protests scheduled for May 1, or May Day. One person said he was interviewed about his plans for May Day. A second person said the police examined political fliers in his apartment, and then arrested him on a warrant for a 2007 open-container-of-alcohol violation.

Officials have yet to respond to questions about the tactics, but one police official, who spoke on condition of anonymity because he was not authorized to speak to reporters about police policy, said the strategy appeared to be an extension of a policy used at events where crowd control could be an issue. Before certain parades that have been marred by shootings, for example, the warrant squads have tracked down gang members who live nearby to execute outstanding warrants, no matter how minor, the official said.

But the department’s use of this tactic as part of its strategy for policing the Occupy Wall Street movement raises new questions about the surveillance efforts by the Police Department, which faces restrictions in monitoring political groups.