Washington: Russian President Vladimir Putin supervised his intelligence agencies' hacking of the US presidential election and turned it from a general effort to discredit the process to a specific attempt to support Donald Trump, three US officials said on Thursday.

Accusations that Russia tried to influence the election by hacking people and institutions, including Democratic Party bodies, has angered President-elect Trump who says he won the November 8 vote fairly. Russian officials have denied all accusations of interference in the US election.

But the US officials said on the condition of anonymity that the US intelligence community is confident its assessment of Russian cyber attacks on the election is accurate.

"This began merely as an effort to show that American democracy is no more credible than Putin's version is," one of the officials said.