National Security Agency director Admiral Michael Rogers has said US intelligence agencies are concerned about the possibility of foreign governments harming the upcoming US elections through cyberattacks. During a Senate Armed Services Committee hearing, Republican Senator John McCain from Arizona and chairman of the committee asked Rogers if Russia could "somehow harm the electoral process" and potentially "disrupt the voting results in the upcoming election", NBC reports.

"We continue to be actively concerned," Rogers responded, Reuters reports.

"I'm not going to characterise this activity," he said. "I think there are scenarios where you could see capability applied."

Rogers noted that "from a defensive standpoint", any attempts to target the US election with cyberattacks would face multiple challenges, given its disparate structure where some states vote electronically while others still vote manually.

While Rogers did not provide any details about intelligence agencies' assessment on the suspected hacking of election computer systems in Arizona and Illinois saying the investigation is still ongoing, he did say that "it continues to be an issue of great focus... for the foreign intelligence community, attempting to generate insights into what foreign nations are doing in this area".

Under Secretary of Defence for Intelligence, Marcel Lettre, said the US government is taking such concerns and activities "quite seriously", adding that an "aggressive investigation" by the FBI and the Department of Homeland Security is currently underway.

US security and intelligence officials as well as experts have expressed serious concerns over the recent rise in cyberattacks against the US and the possibility that foreign actors could use leaked information to negatively influence the general election in November.

While US intelligence officials and cybersecurity experts have said the recent much-publicised hack on the Democratic National Committee, Democratic Congressional Campaign Committee and presidential hopeful Hillary Clinton's campaign could be linked to Russian intelligence services, the Kremlin has aggressively denied the allegations as absurd.

The FBI also recently warned state officials to remain vigilant and boost election security in light of recent evidence that hackers have attempted to breach state voter registration databases in at least two US states. One official told NBC News that Russian intelligence agencies were linked to the intrusions saying, "this is the closest we've come to tying a recent hack to the Russian government". Other officials said although they have not yet confirmed the Russian government's involvement in the breach, they do remain concerned about it.