US security agencies on Monday said Iran was behind a recent hack targeting Donald Trump's presidential campaign, accusing Tehran of seeking to influence the 2024 election.

The statement from the Office of the Director of National Intelligence, the Federal Bureau of Investigation, and the Cybersecurity and Infrastructure Security Agency confirmed the Trump campaign claim from earlier in August that it had been targeted, potentially by Iran.

"We have observed increasingly aggressive Iranian activity during this election cycle, specifically involving influence operations targeting the American public and cyber operations targeting presidential campaigns," the security agencies said.

"This includes the recently reported activities to compromise former president Trump's campaign, which the [intelligence community] attributes to Iran," they said.

In response, Iran's mission to the United Nations denied the country's role in the hack and challenged Washington to release evidence for the claim.

"Such allegations are unsubstantiated and devoid of any standing," the mission said in a statement.

"As we have previously announced, the Islamic Republic of Iran harbours neither the intention nor the motive to interfere with the US presidential election. Should the US government genuinely believe in the validity of its claims, it should furnish us with the pertinent evidence -- if any -- to which we will respond accordingly," the statement added.

The United States goes to the polls on November 5, with both Trump's and Democratic rival Kamala Harris's campaigns saying they had been targeted by cyber attacks in recent weeks. (AFP)