US president-elect Donald Trump said "only 'stupid' people or fools" would dismiss closer ties with Russia, and he seemed unswayed after his classified briefing on an intelligence report that accused Moscow of meddling on his behalf in the election that catapulted him to power.

He said having a good relationship with Russia is a good thing, not a bad thing.

Mr Trump said the US has enough problems without yet another one, and said Russians would respect America far more under his administration than they do with Barack Obama in the White House.

He repeatedly has questioned the assessment by American intelligence agencies that the Kremlin interfered in the 2016 election, and a classified report presented to him on Friday seemed to have little changed his thinking.

The report explicitly tied Russian President Vladimir Putin to election meddling and said that Moscow had a clear preference for Republican Trump.

Outgoing president Barack Obama said Americans should be wary of Vladimir Putin's motives.

"There are republicans who seem to have more confidence in Vladimir Putin than fellow Americans because those fellow Americans are Democrats. That cannot be. We have to remind ourselves we're not on the same team- Vladimir Putin's not on our team."