Nineteen cops at a South Bronx police precinct fudged NYPD crime reports to make statistics look better, downgrading offenses such as theft and assault, Commissioner William Bratton said Friday in announcing disciplinary charges.

Following up on an anonymous tip to the NYPD's Internal Affairs Bureau, an audit of the 40th Precinct's radio calls and 1,558 police reports uncovered 55 suspected instances of a "purposeful misrepresentation of crime data" -- wrongly classifying more serious crimes as less serious ones -- during a four-month period in 2014, Bratton said in a statement.

"I will not tolerate any misconduct that might undermine public confidence in the hard work of the thousands of officers who have made this the safest large city in America," he said.

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Auditors reinterviewed crime victims and reviewed narratives compiled by officers in the audit.

As a result, the 2014 crime statistics for the precinct have been reclassified to reflect an 11.4 percent decrease, not the previously reported 14 percent decrease, the NYPD said.

The accused cops are a lieutenant, eight sergeants, nine police officers and a detective, who are all still assigned to the precinct and are being served with formal departmental charges. Penalties could range from a loss of time off to firing.

Deputy Insp. Lorenzo Johnson, the precinct's commander, was transferred -- to a nonpatrol post in the organized-crime control bureau -- said the NYPD's top spokesman, Deputy Commissioner Stephen Davis.

Johnson is not suspected of complicity, but officials said that since the manipulation of statistics happened on his watch, he should have known, said Lawrence Byrne, deputy commissioner for legal matters. As a precaution, auditors are now scrutinizing his previous command, the 49th Precinct, also in the Bronx.

Captains Endowment Association president Roy Richter, Johnson's union, said more than 96 percent of the audited complaints reviewed were deemed accurate. Richter said Johnson believes the charged officers are "hardworking and conscientious."

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The broad categories of misreported crimes are petty larceny, lost property, misdemeanor assault, criminal mischief and criminal trespass.

While officials wouldn't provide specifics, they gave generic examples of how such a scheme could work: A cellphone stolen from a jacket is misclassified as being lost; shattered glass of a storefront with evidence of attempted burglary is reported as criminal mischief.

In a statement, Patrick Lynch, president of the rank-and-file officers' labor union, the Patrolmen's Benevolent Association, said the union would "vigorously defend these police officers."

"Police officers follow the dictates of their bosses," Lynch said, "or they suffer the consequences."