Bill de Blasio on Saturday called his estranged donor-turned-felon a “liar,” “cheat” and “horrible human being” for testifying in court that the mayor’s team traded nearly $200,000 in political contributions for his personal email, cellphone number and municipal favors.

The claims by donor Jona Rechnitz are “a lot of tales” meant “to save his own skin” as the federal government’s star witness at the federal corruption trial of the city’s former jail-guard union leader.

“I’m not going to let a liar interfere with our work,” de Blasio told reporters after addressing a Shabbos service at the Young Israel of Avenue K synagogue in Midwood, Brooklyn.

Under oath on Thursday and Friday, Rechnitz said he traded money or favors for special treatment from de Blasio, a Democrat; a half-dozen former NYPD officers; and Westchester County Executive Rob Astorino, a Republican.

Rechnitz — who has pleaded guilty and is testifying in the trial of longtime jail union boss Norman Seabrook hoping for leniency — said he had “weekly” chats with the mayor, and got “access” and “results” on at least five matters where he sought help.

But de Blasio said those claims were false, and said he felt vindicated by prosecutors who examined the conduct of the mayor’s team and declined to press charges (but questioned the propriety of the fundraising activity).

Saturday’s 12-minute news conference, announced with 90 minutes notice, came a day after walking away from reporters at publicly scheduled events where reporters shouted questions in vain about Rechnitz’s claims.

De Blasio said he had “no memory” of whether he asked Rechnitz, 34, who was close to Seabrook, to wrangle the union boss who had been criticizing de Blasio’s pick for jails commissioner.

A 2014 email sent from Rechnitz to de Blasio’s BlackBerry, introduced into evidence Friday at trial suggested otherwise, but de Blasio said Saturday: “I have no memory of that at all.”

Asked about the email — in which Rechnitz assures de Blasio, “Norman under control” — de Blasio said, “I don’t remember that email. I have no idea what happened to it.”

The email or its existence was never revealed to the public despite requests from reporters for such documents under the state’s Freedom of Information Law.

Seabrook is charged at Manhattan federal court with pouring millions in retirement dollars into a shaky hedge fund after allegedly receiving kickbacks. Neither de Blasio nor his team are on trial, but much of Rechnitz’s testimony has focused on de Blasio.

De Blasio, who is up for re-election on Nov. 7, said Rechnitz was lying with claims that the two spoke weekly, but he declined to release phone and scheduling records as corroboration.

“You always want everything,” de Blasio told reporters, “and I’m not going to give it to you.”