THE FBI is looking into allegations that sensitive documents from Donald Trump’s presidential campaign were stolen in a cyber intrusion, days after the his campaign claimed to have been hacked by Iran.

In a brief statement the federal police agency said: “We can confirm the FBI is investigating this matter.”

Iran’s mission to the United Nations denied that Tehran was responsible for the hacking.

The Trump campaign provided no specific evidence of Iranian involvement, but the claim came shortly after Microsoft published a report accusing foreign agents of attempting to interfere with this year’s presidential election.

The report claimed that, in June, an Iranian military intelligence unit had sent “a spear-phishing email to a high-ranking official of a presidential campaign from a compromised email account of a former senior adviser.”

US online media firm Politico reported on Saturday that it began receiving emails from an anonymous account on July 22.

The source, identified only as “Robert,” passed on what appeared to be a research dossier that the Trump campaign had apparently prepared on Republican vice-presidential nominee JD Vance. The document was dated February 23, almost five months before Mr Trump selected his running mate.

Two people familiar with the matter, speaking on the condition of anonymity, said that President Joe Biden’s now abandoned campaign had also been targeted in the suspected Iranian hacking.

At least three Biden campaign staff members were targeted with phishing emails, but investigators have uncovered no evidence that the attempt succeeded, one of the people said.

The FBI began investigating that cyber incident in June and intelligence officials believe Iran was behind the attempts, that person said.

As well as Politico, the New York Times and the Washington Post also received leaked material from the Trump campaign, but none has published any details of it — unlike in 2016, when hacked emails to and from Hillary Clinton’s campaign manager John Podesta were covered extensively.