An 18-year-old Bronx resident claims in a new lawsuit that workers at a juvenile detention center have been using their teen jailbirds as “sex slaves.”

Franklin Maldonado, who turns 19 in a few weeks, said he was placed at the Horizon Juvenile Center in the Bronx in 2013 and 2014, when he was just 15 years old.

Instead of protecting him, supervisor Natalie Medford told Maldonado that if he “took care of her needs,” she would protect him from disciplinary action and give him special privileges such as use of her cellphone and the ability to watch “special” movies, according to a Manhattan federal lawsuit.

Maldonado’s lawsuit said Medford would occasionally release him from “the hole,” or a segregated unit for punishment, “and bring him to her office for the purposes of engaging in sexual contact with him.”

While Medford “preyed” on Maldonado, at least one other minor inmate was being “groomed” by another Horizon worker, the lawsuit said.

Male workers looked the other way, including a tour supervisor who allegedly admitted to Maldonado that female guards regularly engaged in sexual conduct with inmates, the lawsuit said.

An operator at Horizon said he could not locate a worker there named Medford.

The city Department of Investigation and the Bronx District Attorney’s Office are investigating the allegations, said a source familiar with the probes.

“We will review the complaint,” said a spokesperson for the city Law Department, which defends the city against lawsuits.