CIA Director John Brennan warns US of Russia’s sophisticated hacking capabilities

File photo of CIA Director John Brennan

CIA Director John Brennan warns that the US must be on guard in the face of Russia’s "exceptionally capable and sophisticated'' cyber capabilities.

"I think that we have to be very, very wary of what the Russians might be trying to do in terms of collecting information in that cyber realm as well as what they might want to do with it," Brennan said Sunday on CBS's Face the Nation.

The CIA chief refused to give a clear answer when asked whether Russia was trying to influence the US presidential election.

However, he added that the FBI was investigating the recent hack ofDemocratic National Committee emails.

"We've known this for quite a while. Their intelligence services are quite active around the world," Brennan said.

"And this is something that we have to make sure that we're on guard for, not just for our national security purposes, but also for making sure that our system of government here is going to be preserved," he added.

Director of National Intelligence James Clapper has been tasked with investigating what officials have described as a “broad covert operation” by Russia to disrupt the November election in the US.

“The Russians hack our systems all the time, not just government but also corporate and personal systems,” Clapper said earlier this month at an intelligence and security summit in Washington.

However, the FBI and other counter-intelligence agencies involved in the probe of the DNC hacking have not yet officially attributed the cyber attack to Russian government hackers.

The disclosures, which included a number of embarrassing internal emails, forced DNC Chairwoman Debbie Wasserman Schultz to step down.

The campaign of Democratic presidential nominee Hillary Clinton has blamed Russia for the cyber intrusion, saying the publication of the stolen emails was aimed at helping Republican nominee Donald Trump win the election.

The Kremlin has rejected the hacking accusations, saying it would work with any US administration if they wanted to.