A plane carrying 35 diplomats expelled from the United States over Russia's alleged meddling in the US presidential election arrived in Moscow early on Monday, Russian state television reported.

A Russian Il-96 plane carrying the diplomats and their families landed at Moscow's Vnukovo airport at 2:05 am after having taken off from Washington on Sunday, state television said.

State television showed the diplomats and their families gathering their luggage on the tarmac in the rain before heading inside the terminal.

US intelligence said the Kremlin ordered a hack-and-release of Democratic Party and Hillary Clinton campaign staff emails in a bid to put Donald Trump in the White House.

Moscow has repeatedly dismissed the allegations.

The expulsions of the diplomats - described as intelligence operatives based at the Russian embassy in Washington and the consulate in San Francisco - were part of a package of sanctions ordered by President Barack Obama on Thursday in the final weeks of his administration.

Obama also ordered the closure of two Russian compounds in New York and Maryland that the US said were used "for intelligence-related purposes".

Russian President Vladimir Putin last week rebuked the outgoing president for "unfriendly steps" amounting to "a provocation aimed at further undermining Russian-American relations".

Putin warned that Russia reserved the right to respond but refrained from ordering the tit-for-tat expulsion of US diplomats from Russia, saying that Moscow's next move will be "based on the policies pursued by the administration of president Donald Trump".

Putin's decision has been interpreted as a sign he is looking to Trump to rebuild US-Russian ties after the US presidential inauguration later this month.

'Disproportionate' move

A top aide to Trump said in an interview aired on Sunday that the White House may have disproportionately punished Russia by ordering the expulsion of Russian diplomats.

Sean Spicer said on ABC's This Week that Trump will be asking questions of US intelligence agencies after Obama imposed sanctions last week.

"One of the questions that we have is why the magnitude of this? I mean you look at 35 people being expelled, two sites being closed down, the question is, is that response in proportion to the actions taken? Maybe it was, maybe it wasn't, but you have to think about that," Spicer said.

Trump was scheduled to have briefings with intelligence agencies this week after he returns to New York.

On Saturday, Trump expressed continued skepticism over whether Russia was responsible for computer hacks of Democratic Party officials.

"I think it's unfair if we don't know. It could be somebody else. I also know things that other people don't know so we cannot be sure," Trump said.