A former US ambassador to the United Nations (UN) has dismissed CIA claims that Russian hackers penetrated both of American’s main political parties and suggested that it could have been carried out by an American actor trying to frame Vladimir Putin's regime.

John Bolton, who is widely tipped for a senior post in Donald Trump’s new regime, questioned the US spy agency’s assessment of the evidence and said intelligence had become "politicised" under President Barack Obama.

Calling the CIA's findings into question, on Sunday Mr Bolton told Fox News' Eric Shawn that “a really sophisticated foreign intelligence service would not leave any cyber fingerprints and yet people say they did leave cyber fingerprints in the hacks regarding our election.”

"We have to know the facts here,” he said of the hacks into both the Democratic National Committee (DNC) and the Republican National Committee (RNC). RNC chairman Reince Preibus has since denied that the party was infiltrated.

“It's not at all clear to me, just viewing this from the outside, that this hacking into the DNC and the RNC computers was not a false flag operation,” Mr Bolton suggested.

Recalling that FBI director James Comey said the Bureau had found “no direct evidence of foreign intelligence service penetration” on the private email server used by Hillary Clinton but said they hadn’t expected to, Mr Bolton said it raised questions about Russian involvement.

He said: “The question that has to be asked is, why did the Russians run their smart intelligence service against Hillary's server, but their dumb intelligence services against the election?"

Mr Bolton, who served as US ambassador to the United Nations between August 2005 and December 2006, added: “We just don't know. But I believe that intelligence has been politicised in the Obama administration to a very significant degree. Now I think the whole thing is called into question, which is why the notion of some kind of independent investigation becomes extremely important.

"I do think it's critical to answer the question I've posed. If you think the Russians did this, then why did they leave fingerprints? Let's hear the debate.”

However, Mr Bolton, who is widely tipped for a senior role in the US State Department – the federal executive that advises the US president on foreign policy issues - under Donald Trump, said he believed “the Russians had both the capability and the intention of doing it”, and he was “not by any means trying to exonerate them.”

President Trump protests Show all 20 1 /20 President Trump protests President Trump protests Patrons hold a sign as people march by while protesting the election of Republican Donald Trump as the president of the United States in downtown Los Angeles, California Reuters President Trump protests Demonstrators rally following the election of Republican Donald Trump as President of the United States, in Oakland, California Reuters President Trump protests Demonstrators march following the election of Donald Trump as President of the United States Reuters President Trump protests Thousands of protesters rallied across the United States expressing shock and anger over Donald Trump's election, vowing to oppose divisive views they say helped the Republican billionaire win the presidency AFP/Getty Images President Trump protests Demonstrators protest outside the Chicago Theatre in Chicago, Illinois Getty President Trump protests A police officer aims a launcher after demonstrators threw projectiles toward a line of officers during a demonstration in Oakland, California Reuters President Trump protests An officer examines a vandalized police vehicle as demonstrators riot in Oakland, California Reuters President Trump protests Demonstrators take over the Hollywood 101 Freeway just north of Los Angeles City Hall in protest against the election of Republican Donald Trump as President of the United States Reuters President Trump protests A woman holds up a sign reading 'Trump you are an Idiot' as demonstrators gather during a protest against President-elect Donald Trump outside the City Hall building in Los Angeles, California EPA President Trump protests A masked demonstrator gestures toward a police line during a demonstration in Oakland, California Reuters President Trump protests Demonstrators protest against the election of Republican Donald Trump as President of the United States, near the Trump International Hotel & Tower in Las Vegas, Nevada Reuters President Trump protests Musician Lagy Gaga stages a protest against Republican presidential nominee Donald Trump on a sanitation truck outside Trump Tower in New York City Getty President Trump protests A woman yells as she takes part in a protest against President-elect Donald Trump in Seattle's Capitol Hill neighborhood AP President Trump protests A man dressed in red-white-and-blue sits on the curb during a protest against President-elect Donald Trump in Seattle's Capitol Hill neighborhood AP President Trump protests A protester sets off fireworks during a protest against President-elect Donald Trumpin Seattle's Capitol Hill neighborhood AP President Trump protests University of California, Davis students protest on campus in Davis, California, U.S. following the election of Donald Trump as President of the United States Reuters President Trump protests An Oakland police officer checks out damage after a window was broken by protesters at a car dealership in downtown Oakland, Calif AP President Trump protests A protester faces a police line in downtown Oakland, Calif AP President Trump protests President-elect Donald Trumpís victory set off multiple protests AP President Trump protests A fire burns during protests in Oakland, Calif AP

Mr Bolton, who on his blog has named Russia in his top five "gravest" threats to US security abroad, alongside Isis, Iran, North Korea and China, added: "If you say they've done that, let me be very clear: either in the cyber world or elsewhere, we should retaliate."

Asked if by using the phrase "false Flag" he was implying that the US government had played a role in the hacking, he said: "We just don't know", although he later insisted that he was not trying to blame the Obama administration for the hack.

"I have never believed that," he said. But he added that the US government under President Obama had tried to "politicise intelligence".

In a bipartisan statement on Sunday four senior US Senators urged Republicans and Democrats to work together to counter the threat of cyber attacks.

They said Russia had "targeted America's democratic institutions" and that the American public must be kept better informed.