Iranian hackers tried to pass information stolen from former President Donald Trump's campaign to President Joe Biden's team earlier in the US election, a joint statement by top US security agencies said on Wednesday.

"The FBI has learned additional details about Iran’s efforts to sow discord and shape the outcome of U.S. elections," the statement said.

"Iranian malicious cyber actors in late June and early July sent unsolicited emails to individuals then associated with President Biden’s campaign that contained an excerpt taken from stolen, non-public material from former President Trump’s campaign as text in the emails," it added.

The investigation comprised the the Office of the Director of National Intelligence, the FBI and the Cybersecurity and Infrastructure Security Agency.

"Wow, just out! the FBI caught Iran spying on my campaign and giving all of the information to the Kamala Harris campaign," Trump said in a post on Truth Social on Wednesday evening.

"Therefore she and her campaign were illegally spying on me. To be known as the Iran, Iran, Iran case! will Kamala resign in disgrace from politics? Will the communist left pick a new candidate to replace her?"

Iranian officials have long called for revenge on Donald Trump who was responsible for the assassination of Quds Force Commander Qassem Soleimani, killed in an airstrike in Iraq.

Iran was also alleged to have meddled in the 2020 presidential election, and US investigators said two Iranian hackers stole confidential US voter information from at least one election website.

They posed as members of the Proud Boys fascist militant group to send threats to Democrats, according to the indictment documents.

Then, according to the FBI, in 2022, Iranian hackers used similar tactics to target voters in the month before the elections.