Washington (AFP) - Russian hackers did not break into the computers of Donald Trump's presidential campaign or active accounts of the Republican National Committee, FBI chief James Comey said Tuesday.

Comey told a Senate Intelligence Committee hearing on Russian interference in the US election that the Russians, in addition to hacking the Democratic National Committee, did break into some state and local Republican campaign systems during last year's campaign.

In addition, they accessed and took information from old, inactive systems of the Republican National Committee.

However, Comey said, "We do not have any evidence that the Trump campaign or the current RNC systems were hacked."

"There is no doubt that they hit the RNC domain," but perhaps could only find the old systems, the Federal Bureau of Investigation director added.

US intelligence chiefs said in a report released Friday that Russian President Vladimir Putin ordered a campaign to interfere with the US election, first to weaken Democratic front-runner Hillary Clinton, and then to boost Trump when he showed the potential to win the November 8 vote.

Democrats say the alleged Russian release of embarrassing Democratic Party documents via WikiLeaks deeply damaged Clinton's campaign, noting there were no Republican files leaked.

But Republicans blame weak Democratic computer security and stress that Trump's election victory was legitimate and unquestionable.