At least two NYPD officers and two karaoke club owners in Queens decided to cooperate in an ongoing probe which led late Tuesday to the arrest of two other officers for allegedly taking bribes and committing other crimes, court papers unsealed in the case indicate.

The investigation began over two years ago after the NYPD ‘s internal affairs bureau received information that some karaoke club owners were paying off officers in order to get tipped off to drug raids, a high-ranked NYPD official said on Wednesday.

Police went to prosecutors in the Queens District Attorneys Office to build the criminal cases which led to the arrests of detective Yatu Yam, 35, and Lt. Robert Sung, 49, both assigned to the 109th Precinct in Flushing. Both officers were arraigned Tuesday in Queens Criminal Court an charges of bribe receiving, official misconduct and other offenses. Yam was freed on $25,000 bail while Sung was being held on $20,000 bond, according to city corrections records.

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“The defendants are accused of taking payment from local club owners to serve as an early warning system, alerting them in advance to police inspections and raids,” Queens District Attorney Richard Brown said in a statement.

Brown said that the criminal complaint charged that the manager of two karaoke clubs paid Yam about $2,000 a month for three years for protection.

Officials said both officers are being defended by attorney James Moschella who didn’t return telephone calls and emails for comment.

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The criminal complaints filed in the cases indicated that two officers from the 109th Precinct, identified only as “John Doe 1” and “John Doe 2,” told investigators how Sung and Yam allegedly interfered with police activity and arrests at clubs which had been raided for drugs. In one instance Yam told one of the cooperating officers he had tipped off a club owner about an upcoming raid, the criminal complaint stated.

The criminal complaint in the case against Sung alleged that an officer had told him about an inspection for drugs in two Queens clubs, JJNY and China Bar, in which suspects were let go after Yam called and told the cop that he couldn’t make arrests because JJNY was Sung’s “place.”

It was unclear from court documents if the officers and the club owners - who were cooperating in the case - may themselves face charges in the continuing investigation. One police official said that at a minimum the officers who provided information to investigators may face departmental charges.

The 109th Precinct covers an area of Flushing with a heavy Asian population which has become a magnet for karaoke clubs, bars and room salons which sell high priced drinks. In a 2006 police scandal, two officers from the precinct’ quality of life unit were arrested on federal charges they took small payoffs from owners of a number of Korean brothels. The officers eventually plead guilty to reduced charges.

In the latest case, Yam has been a police officer since January 2005 while Sung was identified in court papers as being a precinct platoon commander. Both officers were suspended without pay, officials said.