John Flanagan, Lisa-Erika James and Heather Hightower said they were harassed by their former principal at Pan American International High School. View Full Caption BK Nation/Kevin Powell

ELMHURST — Federal prosecutors sued the city Department of Education Thursday on civil rights violations after they say it failed to stop a Queens principal from systematically harassing and demeaning the school's black teachers.

U.S. Attorney Preet Bharara said Thursday the city's DOE stood by and did nothing while Pan American International High School Principal Minerva Zanca compared one of the school's black teachers to "a gorilla in a sweater" with "f---ing nappy hair" and demeaned another for having “big lips.”

“It is nearly unthinkable that, in this day and age, one of the largest and most diverse school districts in the United States would allow racial discrimination and retaliation to flourish. Yet that is what we allege happened at Pan American International High School," Bharara said in a statement Thursday.

The lawsuit also names Superintendent Juan Mendez, who prosecutors say appointed Zanca in the 2012-2013 school year and said the allegations against her were “unfounded” and she "deserves our support," according to the suit.

According to the complaint, Zanca systematically targeted the only three black teachers among the school's 27 teachers — Lisa-Erika James, who was tenured, and John Flanagan and Heather Hightower, who were not.

She tried to pressure Assistant Principal Anthony Riccardo to give Flanagan and Hightower unsatisfactory ratings to deny them tenure before even reading their lesson plans and then retaliated against him when he refused, according to the complaint.

READ THE FULL COMPLAINT

When he offered to help Hightower with her lessons, the principal allegedly told him that he “better not make [Hightower] a better teacher.”

And after Riccardo refused to give an unsatisfactory rating on one of Hightower's lessons, Zanca allegedly accused him of “sabotaging her plan" and asked school security to remove him from the building, the complaint says.

She also tried to drive out James, who ran the school's theater program, by cutting funding to the program and canceling plays before ending it entirely, the feds say.

"Federal civil rights laws prohibit this misconduct. This suit seeks to remedy the violations that occurred at Pan American and ensure that the New York City Department of Education protects its employees’ civil rights in the future,” Bharara said in announcing the lawsuit, which came a day after his office charged the city's Correction Union President Norman Seabrook with fraud and corruption.

According to the U.S. Attorney's Office, the city's Education Department repeatedly refused to take disciplinary action against the principal, allowing her to stay at the helm even after being warned that there was evidence of discrimination by the U.S. Equal Employment Opportunity Commission.

Mendez repeatedly defended Zanca, telling DOE officials the allegations were "manufactured and untrue," the suit says.

Zanca, who joined the DOE in 1988, retired as a principal in June 2015 and has been working as a part-time guidance counselor at Frederick Douglass Academy in Brooklyn, officials said.

A spokesman with the United Federation of Teachers said they reported the issues three years ago.

"When teachers in the school got no relief the UFT and community leaders protested on the steps of Tweed. Since then, we have met consistently with the DOE about the management problems at the school," the spokesman said.

Department of Education spokeswoman Devora Kaye said “All employees’ work environments must be safe and supportive, and we have zero tolerance for any discrimination."

►READ THE U.S. ATTORNEY'S COMPLAINT HERE: Feds Sue City Education Department Over 'Racist' Principal

►READ MORE: 2013 Letter to Superintendent Mendez from Pan Am International HS Teachers