US intelligence officials say Iran is responsible for the hack of Donald Trump’s presidential campaign.

It was the first US government attribution of responsibility for a cyber intrusion that the Republican nominee had previously linked to Tehran.

The FBI and other federal agencies said Iran perceived this year’s presidential election to be particularly consequential and was determined through the hacking operation and other activities to interfere in American politics and “to stoke discord and undermine confidence in our democratic institutions.”

“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,” said a joint statement from the FBI, the Office of the Director of National Intelligence and the Cybersecurity and Infrastructure Security Agency.

The statement said the Iranian hackers have “sought access to individuals with direct access to the presidential campaigns of both political parties.”

The FBI has been investigating attempts to gain access to Democrat Kamala Harris’ campaign.