New York: US intelligence officials are convinced that Russia meddled in the presidential race. But that hasn't changed President-elect Donald Trump's call for warmer relations with Moscow.

Trump declared in a series of tweets on Saturday that "only 'stupid' people or fools" would come to a different conclusion.

"Having a good relationship with Russia is a good thing, not a bad thing," he stated from Trump Tower, adding: "We have enough problems without yet another one."

American intelligence officials on Friday briefed the president-elect on their conclusions that the Kremlin interfered in the 2016 election in order to help him win the White House.

An unclassified version of the report explicitly tied Russian President Vladimir Putin to election meddling and said that Moscow had a "clear preference" for Trump in his race against Hillary Clinton.

Trump has repeatedly sought to downplay the allegations, alarming some who see a pattern of scepticism directed at US intelligence agencies and a willingness to embrace Putin.

During the election, Trump praised the Russian strongman as a decisive leader, and argued that the two countries would benefit from a better working relationship, though attempts by the Obama administration at a "Russian reset" have proved unsuccessful.

At the same time, intelligence officials believe that Russia isn't done intruding in US politics and policymaking.

Immediately after the November 8 election, Russia began a "spear-phishing" campaign to try to trick people into revealing their email passwords, targeting US government employees and think tanks that specialise in national security, defence and foreign policy, the unclassified version of the report said.

The report said Russian government provided hacked emails from the Democratic National Committee and Clinton's campaign chairman, John Podesta, to the anti-secrecy group WikiLeaks.

The website's founder, Julian Assange, has denied that it got the emails it released from the Russian government. The report noted that the emails could have been passed through middlemen.

Russia also used state-funded propaganda and paid "trolls" to make nasty comments on social media services, the report said.

Moreover, intelligence officials believe that Moscow will apply lessons learned from its activities in the election to put its thumbprint on future elections in the United States and allied nations.

The public report was minus classified details that intelligence officials shared with President Barack Obama on Thursday.

In an interview with The Associated Press after the briefing, Trump said he "learned a lot" from his discussions with intelligence officials, but he declined to say whether he accepted their assertion that Russia had intruded in the election on his behalf.