By Jack Queen and Jasper Ward

(Reuters) -Donald Trump was hit on Friday with a $5,000 fine by a New York judge for violating a gag order barring the former U.S. president from disparaging court staff during a civil fraud trial in which he is accusing of unlawfully inflating his net worth to dupe lenders.

Future violations by Trump could be punished by steeper fines and possible imprisonment, Justice Arthur Engoron said in an order. The judge noted that the violation appeared inadvertent, but added, "Make no mistake: future violations, whether intentional or unintentional, will subject the violator to far more severe sanctions."

Engoron said in the order that a social media post by Trump attacking the judge's clerk - which was deleted from the former president's Truth Social platform - had remained visible on his campaign website two weeks after he had ordered it taken down.

Trump is the frontrunner for the Republican nomination to challenge Democratic President Joe Biden in the 2024 U.S. election, holding a commanding lead over his rivals despite mounting legal troubles and court-ordered restrictions on his public statements.

Engoron, presiding over the trial on charges brought by New York state Attorney General Letitia James, imposed a limited gag order on Oct. 3 after Trump in a social media post shared a photo of the judge's top clerk posing with U.S. Senate Majority leader Chuck Schumer, a critic of the former president, and called her the senator's "girlfriend."

Engoron said in imposing the gag order that comments directed at his staff were "unacceptable, inappropriate and will not be tolerated under any circumstances."

Trump at times has appeared in person at the ongoing trial, attacking James and Engoron in inflammatory remarks to reporters outside of the courtroom.

Trump did not attend Friday's hearing at which, according to U.S. media accounts, his lawyers said the post remaining visible was inadvertent and offered an apology to the judge.

The lawsuit by James accused Trump of inflating the values of his properties by billions of dollars in statements to banks, reaping hundreds of millions of dollars in ill-gotten savings on loan interest. Trump is also accused of manipulating asset values to dupe insurers.

Trump, who has sought to portray the case as intended to hurt him politically, has denied wrongdoing and defended his asset valuations. He has said banks conducted their own due diligence and profited on the loans.

Trump faces criminal charges in four other cases involving his efforts to undo his loss in the 2020 election, his handling of classified documents after leaving office and hush money paid to a porn star. Trump has denied wrongdoing and pleaded not guilty in those cases. He also faces a January civil damages trial for defaming a writer who accused him of rape, which he denies.

On Oct. 17, a Washington federal judge overseeing a case accusing Trump of illegally attempting to overturn his defeat in the 2020 presidential election barred Trump from making public statements that "target" U.S. prosecutors, court staff and potential witnesses involved in the case.

Trump is appealing that order.

(Reporting by Jasper Ward and Jack Queen; editing by Costas Pitas, Will Dunham and Noeleen Walder)