On Thursday, the federal monitor overseeing Rikers Island rejected the administration’s plan to isolate dangerous inmates at the city’s jails — another blow for the troubled jail complex.

The plan was for the city to use a new housing unit, known as RMAS, as a more humane replacement for solitary confinement. But the monitor, Steve Martin, found the city was not ready to implement it, and its current structure posed “safety risks.” Martin questioned whether the city had adequate staff to make it happen.

In the monitor’s court filing late Thursday, he also found “the overall situation in the jails remains chaotic and incidents involving serious harm and tragic fatalities are all too frequent.”

In response, the city’s correction commissioner, Louis Molina, sent NY1 this statement: “We remain committed to a restrictive housing model that creates the most humane conditions possible while maintaining safety and holding those who commit violence in our jails accountable. At the same time, we take the requirements of the Action Plan seriously and will be working with the Federal Monitor on a path forward as ordered by the Court.”