A police sergeant says the NYPD covered up the most damning allegations in its embarrassing 2015 karaoke bar bribery scandal including a plan to frame a commanding officer for rape.

In a notice he plans to sue the city for $35 million, whistleblower Sgt. Steven Lee alleges police brass hid the massive scale of the Queens nightclub corruption.

Just two cops were arrested in the crackdown — Lt. Robert Sung and Det. Yatyu Yam. They were accused of taking payments in exchange for advance warning to Flushing, Queens karaoke club owners about police raids. They were suspended but eventually reinstated to the force.

But Lee, who was an undercover officer in the Internal Affairs probe, says the corruption ran much deeper and involved around 100 cops.

At the heart of his notice of claim, a precursor to a lawsuit, is Jimmy Li, owner of two Flushing clubs — JJNY Cafe on Northern Boulevard and CEO KTV & Cafe on College Point Boulevard.

Lee was put on the internal probe after Sung allegedly told him that he planned to frame Thomas Conforti, the commanding officer of the 109th Precinct, as a favor to the club owner.

Sung planned to falsely accuse him of raping a female escort in one of the karaoke joints— to protect the bribe racket from scrutiny, Lee claims.

In an interview with The Post, Lee recounted driving Sung to a pizzeria when the fellow cop confided in him about the plan to get an escort to allege that the commanding officer of the precinct had raped her.

Lee reported that to superiors but they did nothing, he claims.

Shortly after Sung and Yam were arrested, Li — who allegedly paid cops tens of thousands in bribes to protect his clubs — showed up at then-Police Commissioner Bill Bratton’s holiday party.

“He was telling people he was friends with the PC,” Lee said.

When Lee brought higher-ups evidence of criminal activity by numerous cops, including a chief, detectives, sergeants and lieutenants, he was told to limit the scope of his probe, the claim says.

Lee says video and audio recordings of the additional corruption mysteriously “malfunctioned” after he handed it over.

Lee questioned the integrity of the investigation, but Bratton subjected him to internal investigations and barred him from promotions, his claim alleges.

“The police always claim they can clean up after themselves, but they can’t,” said Lee’s attorney, Eric Sanders. “The watchers are corrupt. The whole internal investigation process is a big joke.”

Marvyn Kornberg, lawyer for Robert Sung, responded to the notice of claim, saying: “It appears he is suing the city for 35 million dollars because IAB didn’t fully believe his allegations. Apparently the District Attorney felt the same way since the felony charges against Sung were dropped to the lowest of misdemeanors.”

An NYPD spokesman declined to comment. Bratton did not immediately return requests for comment. Li also did not return a message.