A Brooklyn federal judge yesterday made permanent his earlier decision to bar the city from hiring new firefighters based on an entrance test he said discriminates against blacks and Hispanics.

“The Fire Department’s use of discriminatory testing procedures is a decades-old problem,” wrote Judge Nicholas Garaufis in his ruling.

He emphasized that the city can still hire the personnel it needs — as long as it uses one of five court-approved methods for ensuring that firefighter recruits better represent a cross-section of the city’s population.

In September, the city had rejected the options, arguing that they represented “some form of race-based quota.”

The city had also argued that the judge’s earlier temporary ruling was creating a manpower shortage, endangering the public’s safety.

The judge countered yesterday that the city’s argument lacks credibility, given that the FDNY is considering closing firehouses and reducing staffing levels.

The decision now makes permanent the interim order issued this summer.

The Fire Department declined to comment.