US federal investigators are investigating whether Iranian hackers participated in hacking the computers of people associated with Donald Trump and Kamala Harris, sources familiar with the investigation said, reports CBS News.

The FBI started the respective investigation in early summer, the sources informed.

Cybercriminals linked to Iran are suspected of what happened in the US.

The news comes after the FBI confirmed on Monday that it is investigating the involvement of Iranian hackers in the activities of the Trump campaign.

Former US President Donald Trump's campaign announced on Saturday that its computers were hacked and suggested that Iranian entities participated in the theft and distribution of classified internal documents.

But Vice President Kamala Harris’ campaign denies the possibility of hacking. The campaign monitors and defends against cyberattacks, and it is not aware of any breach of the security of its systems, said Harris' campaign.