A New Jersey correction officer claims he was demoted and retaliated against for reporting that his white superior choked a black inmate who was being processed in the county jail, new court papers allege.

Anthony Smith — a CO in Hudson County for 20 years — said the Department of Corrections and Rehabilitation “unleashed a torrent of reprisal” against him after he made a complaint alleging Sgt. Mario Fernandez had choked an inmate in a mugshot photo, according to his lawsuit filed Friday.

“When you speak out against someone especially inside your department, this is what happens to you,” Smith, 46, told The Post. “You basically get blackballed.”

The correction officer had received a mugshot photo, obtained by The Post, showing the hand of a white person around the neck of a black inmate with his eyes closed.

“I was disgusted,” said Smith, who in 2008 founded outreach group the Blacks and Law Enforcement Servicing the Community Organization. “Something has to be done about it.”

Fernandez — who was allegedly “notorious” for being aggressive with inmates and coworkers — was ultimately suspended for 45 days for the incident, according to the Hudson County suit.

Smith, of Somerset, began working for the department in 2003 and was promoted in 2020 to a community relations officer — a role that includes recruiting, mentoring students, attending proceedings with juveniles and other out of jail responsibilities.

But after he reported Fernandez on Aug. 26, 2022, Smith’s career came to a grinding halt, the lawsuit alleges.

Instead of taking “proper remedial action,” Smith claims department officials broadcasted his complaint “throughout the corrections facility,” according to the filing.

Then three days later on Aug. 29, Capt. Paul Morales repeatedly pressed Smith to reveal who had sent the photo to him with the “obvious implication” being that Morales “wanted to expose the whistleblower and subject them to retaliation,” the suit alleges.

Smith refused to say which employee sent him the photo.

Fernandez was suspended over the incident a few weeks later, but Morales allegedly expressed that he was upset about Smith coming forward, the court papers state.

“You know, that’s not right,” Morales said, according to the lawsuit. “That shouldn’t be happening to my supervisors. I don’t know how this got out.”

“A brutal campaign of retaliation” ensued, including Smith being demoted on Dec. 28 and sent back to work in the Kearny jail beginning on Jan. 1, 2023, the court documents claim.

Smith was told his new assignment was due to the the jail being “short manpower” — but he claims this was merely a “pretext” since the lockup was short-staffed throughout the pandemic yet he was not sent back to work there during that time, the suit alleges.

“I was upset. I was embarrassed,” Smith told The Post of the demotion that landed him working in the jail again. “I do the right thing and I’m being punished for it.”

Smith says he met with the county director three times to discuss getting his old job back but the director wouldn’t budge.

Local students, community leaders and Kearny Mayor Albert G. Santos have called for Smith’s return to his post and held three “separate rallies” for the correction officer.

Meanwhile Smith’s coworkers started “treating him in an extremely disrespectful manner” and isolating him at work, the suit claims.

And Smith was assigned to undesirable postings usually given to new workers and was “constantly” shuffled around the jail, the filing alleges.

He was also posted to the same unit as Fernandez, and was forced to work and interact with Fernandez “on a daily basis,” the suit claims.

“Each such interaction is negative, with defendant Fernandez treating Plaintiff in a demeaning and degrading manner,” the suit charges.

On March 15, when Smith made a complaint about allegedly being retaliated against, the county conducted “a halfhearted investigation,” the suit alleges.

Smith is suing for unspecified damages.

“The thing that strikes me most about this case is that Anthony knew full well that reporting a sergeant would get him blackballed,” said his lawyer Christian McOmber, of McOmber McOmber & Luber P.C. “But he crossed the ‘blue wall’ because he is a man of honor and does the right thing no matter the cost.”

Hudson County and Fernandez didn’t return requests for comment.