Feds investigating Mayor Bill de Blasio donor and pal Jona Rechnitz had to read The Post to find out that he treated NYPD brass to a 2014 flight with a hooker, sources say.

Investigators were shocked when The Post reported that Rechnitz, who pleaded guilty in March to making contributions for favorable treatment, had a prostitute named Candi on a private jet where she initiated two high-ranking cops into the Mile-High Club. Rechnitz and pal Jeremy Reichberg were flying the officers to Las Vegas.

After seeing the story, investigators pulled the jet’s passenger records, and lo and behold, there was Candi, according to a person with direct knowledge of the situation.

Rechnitz, who is testifying in a bribery case against ex-correction officers union chief Norman Seabrook, revealed Friday that he also bought sex for four other cops in 2013.