NEW YORK (AP) — The number of street stops made under the New York Police Department's heavily criticized "stop-and-frisk" strategy has dropped sharply, police officials said Friday.

The nation's largest police department stopped 133,934 people in April, May and June — down from 203,500 for the first quarter of this year. This year's second-quarter total marked a 25-percent decline compared with the same three months in 2011.

The strategy has resulted in well over a half-million stops each year — there were a record 684,330 last year — mostly of black and Hispanic men. Only about 10 percent are arrested.

Civil rights advocates say the practice is illegal and racially biased. Police officials call it a vital crime-fighting tool that has curbed shootings and other violence.

Police Commissioner Raymond Kelly told reporters on Friday that the decline was partly the result of a reduction in the number of rookie officers available to assign to high-crime neighborhoods. He also credited increased training of officers about what constitutes reasonable suspicion to stop, question and possibly frisk someone.

"We're hopeful the training is improving the quality of the stops," Kelly said.

In a statement, New York Civil Liberties Union Executive Director Donna Lieberman called the recent results encouraging but not enough to repair the trust that's been damaged in minority communities.

"If past is prologue, we can expect that NYPD officers subjected at least 1,000 innocent New Yorkers a day to humiliating and unjustified street stops," Lieberman said. "That is nothing to brag about."