NEW YORK (AP) — The New York Police Department has secretly labeled entire mosques as terrorist organizations, a designation that allows police to use informants to record sermons and spy on imams, often without specific evidence of criminal wrongdoing.

Designating an entire mosque as a terrorism enterprise means that anyone who attends prayer services there is a potential subject of an investigation and fair game for surveillance.

Since the 9/11 attacks, the NYPD has opened at least a dozen "terrorism enterprise investigations" into mosques, according to interviews and confidential police documents. The TEI, as it is known, is a police tool intended to help investigate terrorist cells and the like.

Many TEIs stretch for years, allowing surveillance to continue even though the NYPD has never criminally charged a mosque or Islamic organization with operating as a terrorism enterprise.

The documents show in detail how, in its hunt for terrorists, the NYPD investigated countless innocent New York Muslims and put information about them in secret police files. As a tactic, opening an enterprise investigation on a mosque is so potentially invasive that while the NYPD conducted at least a dozen, the FBI never did one, according to interviews with federal law enforcement officials.

The strategy has allowed the NYPD to send undercover officers into mosques and attempt to plant informants on the boards of mosques and at least one prominent Arab-American group in Brooklyn, whose executive director has worked with city officials, including Bill de Blasio, a front-runner for mayor.

The revelations about the NYPD's massive spying operations are in documents recently obtained by The Associated Press and part of a new book, "Enemies Within: Inside the NYPD's Secret Spying Unit and bin Laden's Final Plot Against America." The book by AP reporters Matt Apuzzo and Adam Goldman is based on hundreds of previously unpublished police files and interviews with current and former NYPD, CIA and FBI officials.

The disclosures come as the NYPD is fighting off lawsuits accusing it of engaging in racial profiling while combating crime. Earlier this month, a judge ruled that the department's use of the stop-and-frisk tactic was unconstitutional.

The American Civil Liberties Union and two other groups have sued, saying the Muslim spying programs are unconstitutional and make Muslims afraid to practice their faith without police scrutiny.

Both Mayor Mike Bloomberg and Police Commissioner Raymond Kelly have denied those accusations. Speaking Wednesday on MSNBC's Morning Joe, Kelly reminded people that his intelligence-gathering programs began in the wake of 9/11.

"We follow leads wherever they take us," Kelly said. "We're not intimidated as to wherever that lead takes us. And we're doing that to protect the people of New York City."

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