WASHINGTON  — The FBI said Monday it is investigating allegations that sensitive documents from the Trump campaign were stolen in a cyber intrusion days after the campaign declared it had been hacked by Iran.

The FBI released a brief statement reading, “We can confirm the FBI is investigating this matter.”

The campaign provided no specific evidence of Iran’s involvement, but the claim came shortly after Microsoft issued a report detailing foreign agents’ attempts to interfere in the U.S. campaign in 2024.

The report cited an instance of an Iranian military intelligence unit in June sending “a spear-phishing email to a high-ranking official of a presidential campaign from a compromised email account of a former senior advisor.”

Iran’s mission to the United Nations, when asked about the claim of the Trump campaign, denied being involved. “We do not accord any credence to such reports,” the mission said. “The Iranian government neither possesses nor harbors any intent or motive to interfere in the United States presidential election.”

In 2016, intelligence officials said Russian hackers obtained thousands of emails from the Democratic National Committee, the Democratic Congressional Campaign Committee, and the personal account of Clinton’s campaign chairman, John Podesta. The initial batches came out in the summer, as Clinton clinched the Democratic nomination.

Trump’s campaign blasted the the most recent cyber intrusion.

“Any media or news outlet reprinting documents or internal communications are doing the bidding of America’s enemies and doing exactly what they want,” Steven Cheung, the campaign’s communications director, said in a statement on Saturday announcing that the campaign had been hacked.

Politico first reported the hack into the Trump campaign earlier Saturday. The outlet reported that it began receiving emails on July 22 from an anonymous account. The source — an AOL email account identified only as “Robert” — passed along what appeared to be a research dossier the campaign had apparently done on the Republican vice presidential nominee, Ohio Sen. JD Vance. The document was dated Feb. 23, almost five months before Trump selected Vance as his running mate.

In 2016, when Clinton’s campaign was hacked, the material was released through third parties, including the online site Wikileaks, which began to publish daily tranches of Democratic documents in October, just after a videotape of Trump bragging about how he’d sexually assaulted women was disclosed.

Trump routinely touted the Democratic leaks at his campaign rallies, including declaring at one: “I love Wikileaks.”

The analysis from Microsoft of the Trump campaign hack stated that, “Iranian cyber-enabled influence operations have been a consistent feature of at least the last three U.S. election cycles. Iran’s operations have been notable and distinguishable from Russian campaigns for appearing later in the election season and employing cyberattacks more geared toward election conduct than swaying voters.”

“Recent activity suggests the Iranian regime — along with the Kremlin — may be equally engaged in election 2024,” Microsoft concluded.