He couldn’t keep it zipped for long.

Former President Donald Trump exploded at his Manhattan civil fraud trial Monday minutes after making a zipped-lips gesture to reporters — and accused the judge who has branded him a fraudster of mounting a “fraud” himself.

“He called me a fraud and he didn’t know anything about me!” the 2024 GOP presidential frontrunner yelled — pointing at Manhattan Supreme Court Justice Arthur Engoron.

“The fraud is on the court, not on me.”

Trump’s tirade came at around noon — midway through his about four hours of testimony in New York Attorney General Letitia James’ $250 million lawsuit accusing him of inflating his wealth by billions per year to save money on loan and insurance terms.

“She’s a political hack,” Trump shouted of James, who was sitting calmly in the first row of the gallery.

Gesturing furiously with his hands, the real estate tycoon then accused James of attempting to use “this case to become governor” and having used it to gain her current post.

“The fraud is her!” he said.

Earlier in the day, the judge had chastised Trump, 77, for giving “repetitive” and “non-responsive” answers to simple “yes-or-no questions” by AG attorneys about whether he stood by the annual financial filings at the core of the suit.

“This is not a political rally,” Engoron told the former president. “Please, just answer the questions, no speeches.”

The judge — who is deciding the case because the type of suit James brought calls for a bench trial — at one point snapped at Trump’s attorneys to “control your client.”

“I would beseech you to control him if you can. If you can’t, I will,” the exasperated jurist said, before threatening to boot Trump from the witness stand and draw “negative inferences” in his absence.

Trump testified for the first two hours of the day in nearly hushed tones — a far cry from the bluster he normally displays in public.

During a brief morning break, after being warned by the judge not to discuss his testimony until it ended, Trump made a zipped-lips gesture to reporters in the hallway.

His rant came just minutes later, when the trial reconvened, with Trump’s courtroom decorum beginning to break down after AG lawyer Kevin Wallace grilled him about the 2014 version of his financial statement.

“People don’t know how good a company I built! You know why? Because people like you try and demean me and hurt me, probably for political reasons,” said a visibly agitated Trump, raising his voice for the first time all day.

He claimed Engoron and James were “trying to hurt” him, before accusing them of “fraud.”

“When you rule Mar-A-Lago is worth $18 million and she rules it’s worth $25 million, either people are very stupid or there’s a fraud. The fraud is on behalf of the court,” he said.

In a bombshell decision from days before trial began, Engoron found Trump responsible for some of James’ main fraud allegations, citing a Florida official’s appraisal of the Palm Beach golf club at a maximum of $27 million while Trump has claimed it’s worth as much as $1.5 billion.

Trump’s tax broker was forced to admit to authorities in 2020 that Mar-a-Lago had a market value of just $27 million — not the $517 million claimed in other documents — because Trump labeled the property a “social club” and not a private residence, which carried massive tax benefits, trial evidence has revealed.

“He said I’m a fraud because I didn’t value my property correctly,” Trump loudly ranted about Engoron. “He’s the one who didn’t value my property correctly.”

Trump also insisted he did a “great job” as president.

After Trump rambled for several minutes straight, Wallace, the AG’s office attorney, asked, “Are you done?”

“Done,” Trump responded.

The AG’s lawsuit could lead to Trump being forced to pay millions and cede control of Midtown’s Trump Tower and his other Big Apple properties.

James alleges that from 2011 through 2021, Trump inflated his assets by billions a year on “statements of financial condition” in order to get an edge with banks and insurers.

At times, the real estate mogul acknowledged Monday that he helped his accountants assemble the statements — which Engoron found in a pre-trial ruling were riddled with “persistent fraud.”

“If somebody would ask me for an opinion, I would give it to them,” he testified, adding “I think I’ve shown I know more about real estate than other people.”

But at other times, he claimed that Deutsche Bank and other financial institutions didn’t rely on the filings before issuing their loans — despite being confronted with contracts calling for Trump’s business to divulge the documents as a condition of getting the financing.

“It just wasn’t very important, you’ve made it very important,” Trump quipped to Wallace.

Trump went on a two-minute rant outside the courtroom after the trial wrapped for the day, telling reporters that the case should be “dismissed immediately.”

“The fraud was on behalf of the court. The court was the fraudster in this case,” he said.

“Everything we did was absolutely right,” Trump continued.

“I think it’s a very sad day for America,” he said, “but anyway, this is a case that should have never been brought.”

In her own statements outside court, James was calm and matter of fact when describing Trump’s antics, telling reporters, “He rambled, he hurled insults, but we expected that.

“At the end of the day the documentary evidence demonstrates that in fact he falsely inflated his assets to basically enrich himself and his family,” she said, adding Trump “persistently engaged in fraud.”

The trial will resume Wednesday morning with Trump’s daughter Ivanka on the stand as the AG’s last witness.