Former US President George W Bush urged the country to show "resolve and resilience" against external attacks on their democracy and confront "a new era of cyber threats". During a forum at the George W Bush Institute in New York, the former president said Russia's alleged cyberattacks and influence campaign during the 2016 election "feed and exploit our country's divisions" and turn "Americans against each other".

Bush highlighted recommendations from a call to action paper titled "The Spirit of Liberty: At Home, In The World" by two scholars, Pete Wehner and Tom Melia, at the institute.

"First, America must harden its own defenses," Bush said. "Our country must show resolve and resilience in the face of external attacks on our democracy. And that begins with confronting a new era of cyber threats."

He said the country is currently experiencing the "sustained attempt" by a "hostile" foreign power to exploit and divide American citizens.

"According to our intelligence services, the Russian government has made a project of turning Americans against each other," Bush said. "This effort is broad, systematic and stealthy, it's conducted across a range of social media platforms. Ultimately, this assault won't succeed.

"But foreign aggressions — including cyber-attacks, disinformation and financial influence — should not be downplayed or tolerated. This is a clear case where the strength of our democracy begins at home. We must secure our electoral infrastructure and protect our electoral system from subversion."

Bush's remarks come as tech giants Facebook, Twitter and Google have faced intense scrutiny over their inadvertent role in the Russian misinformation campaign during the race to the White House. Facebook recently disclosed it sold $100,000 (£75,648) worth of politically divisive ads to inauthentic ads linked to Russia from June 2015 to May 2017 that were seen by 10 million people. It turned over 3,000 Russian-linked ads to congressional intelligence committees.

It was also reported that Russian operatives used the site to remotely organise anti-immigrant protests and pro-Trump rallies on US soil.

Twitter said it discovered 201 Russian accounts on its site that were also connected to the Facebook ads. Google revealed that Russian operatives spent tens of thousands of dollars on YouTube, Gmail and Google search ads.

Facebook, Twitter and Google executives have been invited to testify at a hearing before the Senate Intelligence Committee on 1 November to examine how foreign entities may have used their platforms to influence the election. Twitter's Sean Edgett and Facebook's general counsel Colin Stretch will testify at the hearing.

In January, US intelligence agencies assessed with "high confidence" that Russian President Vladimir Putin directed a complex influence campaign that included cyberattacks, misinformation, leaks and more to undermine American democracy, hurt Hillary Clinton's chances and help Donald Trump win the election.

The Kremlin has dismissed the allegations as "baseless" and denied any involvement in the DNC hack. Trump has repeatedly referred to the ongoing Russia investigation as a "witch hunt".

Multiple congressional committees along with special counsel Robert Mueller are currently investigating Russian meddling in the election and any ties between Trump's team and Moscow.