President Barack Obama has revealed he ordered Russian President Vladimir Putin to “cut it out” in a conversation about email hacking ahead of the US election.

Implying that Vladimir Putin knew about the hacks, Barack Obama said: “Not much happens in Russia without Vladimir Putin.”

Barack Obama said he had warned the Russian president of serious consequences at a summit in September.

A month later, the United States accused Russia of meddling in its democratic process.

Barack Obama has promised a “proportional” response to the hacking of the Democratic Party and of emails belonging to defeated presidential candidate Hillary Clinton’s campaign chairman.

The president appeared to suggest that the US could go on the offensive with its own cyber muscle, stating: “Whatever they do to us, we can potentially do to them.”

Barack Obama’s comments came during his last news conference of the year.

However, he did not criticize his successor, Republican Donald Trump, by name, but said some Republicans were failing to acknowledge the seriousness of Russia’s involvement in the US election.

Barack Obama also expressed bewilderment over GOP supporters who say they approve of Vladimir Putin, declaring: “Ronald Reagan would roll over in his grave.”

The president urged Donald Trump to back a bipartisan investigation into Russian cyber intrusions.

Earlier this week, the president-elect poured scorn on US intelligence claims that Russian hackers helped swing the election in his favor, calling them ridiculous and politically-motivated.

Donald Trump tweeted: “Can you imagine if the election results were the opposite and WE tried to play the Russia/CIA card. It would be called conspiracy theory!”

CIA Director John Brennan told employees on December 16 that the FBI agrees with the CIA’s conclusion that Russia’s goal was to help Donald Trump win.

The Kremlin denies US claims that Russia hacked official emails, and has called them “indecent”.

Vladimir Putin’s spokesman said: “They need to either stop talking about this or finally present some sort of proof.”

Russia’s response came as Hillary Clinton attributed her election defeat to Russian hacking for the first time.

Hillary Clinton told party donors that Vladimir Putin had a “personal beef” against her for describing Russia’s parliamentary elections five years ago as rigged.

The Democratic candidate also cited the release of a letter by FBI director James Comey as having lost her close races in key states.

James Comey made headlines when he announced a new inquiry into Hillary Clinton’s email server 11 days before the presidential election. The matter was dropped two days before Americans voted.

The FBI had previously concluded that Hillary Clinton had been “extremely careless” over her use of a private email server while secretary of state, but there were no grounds for any charges.