The FBI is investigating one of its own Twitter accounts after it posted a dossier on Bill Clinton’s controversial pardon of Marc Rich in 2001, it was reported Thursday.

The FBI’s assistant director in the office of professional responsibility, Candice Will, confirmed the investigation had been referred to the FBI’s inspection division, according to Think Progress, a Web site of the Center for American Progress, which is tied to Hillary Clinton campaign chair John Podesta.

Despite Will’s statement, an FBI official told The Post a computer glitch was responsible for the unexpected release right before the election and said it’s “unlikely” an investigation will actually take place.

The verified Twitter account @FBIRecordsVault had been dormant for more than a year when it came alive on Sunday, spewing 20 short statements and links to investigations related to Gen. David Petraeus, Hillary Clinton’s use of a private server and Donald Trump’s father.

“Fred C. Trump: Fred C. Trump (1905-1999) was a real estate developer and philanthropist,” read a tweet from the account. The tweet linked to an eight-page dossier on Donald Trump’s father, including an FBI memo from March 28, 1966.

The tweets related to Petraeus and Clinton also linked to dossier files.

But it was on Tuesday when alarm bells rang at the Clinton campaign as the FBI site spit out this message: “William J. Clinton Foundation: This initial release consists of material from the FBI’s files related to the Will . . .”

The tweet was accompanied by a link to 129 pages of heavily redacted documents from Clinton’s pardoning of financier Rich 15 years ago.

Rich received the pardon on Jan. 20, 2001 — Clinton’s final day in the White House. Rich had been indicted on tax-evasion, wire-fraud and racketeering charges and had fled the United States to Switzerland.

It was widely reported at the time that US Attorney Mary Jo White launched a grand-jury investigation into whether Rich’s ex-wife, New York songwriter Denise Rich, procured the pardon by making large donations to the Democratic Party and the Clinton Foundation.

An FBI official said, “It is unlikely that an investigation will be necessary or appropriate based on the fact that an automated computer procedure resulted in this posting.”

The official said the agency ran a patch on its Web site on October 30, which sent previously posted material to its Twitter feed.

But the Rich posting was new.

“The Marc Rich stuff was posted Tuesday, Nov. 1, and because the system was working, it went up immediately,” the official told the Post.

There is “absolutely” no connection to the election, he said.

The Clinton team has described the timing as “odd.”

Clinton aides have accused FBI Director James Comey of interfering in the election after he sent a letter last week to lawmakers about new evidence in the Clinton e-mail probe.