Russian hackers targeted election-related systems in 21 states during the 2016 presidential election, a US official has confirmed.

Opening a Congressional session, the vice chair of the Select Committee on Intelligence, Mike Warner, described the hacking as marking a watershed in political history.

"At a minimal cost, Russia sowed chaos in our political system and undermined faith in our democratic process," he told attendees.

Testifying before the Congressional committee, an official from the Department of Homeland Security (DHS) confirmed the number of states targeted by hackers seeking to affect the electoral results.

Jeanatte Manfra, the acting deputy undersecretary of cybersecurity at the DHS, told the Congressional committee the agency had evidence of 21 states being targeted.


Ms Manfra declined to disclose which states were targeted and how successful the attempts at hacking were, other than to affirm that the result of the election was not in question.

Image: Committee chairman Richard Burr

The chairman of the select committee, Richard Burr, asked: "But in no case were actual vote tallies altered in any way shape or form?"

"That is correct," the DHS acting deputy undersecretary responded.

Her statements were the first public confirmation of the scale of foreign interference in the US presidential election.

While the attacks achieved varying levels of success in penetrating their target systems, the access was not enough to allow the attackers to manipulate the ballots themselves.

Last year, reports circulated that hackers had targeted the voter registration systems in the states of Illinois and Arizona.