White House hopeful Bernie Sanders has demanded Russia "stay out" of US elections after reports emerged that Moscow was interfering in the presidential race to help the Democratic frontrunner's campaign.

The Washington Post reported that US officials briefed Mr Sanders - and President Donald Trump - about the efforts by Russia, although it was unclear what form the assistance to Sanders has taken.

"My message to Putin is clear: stay out of American elections, and as president I will make sure that you do," Sanders said in a statement. 

US intelligence had concluded that Russia interfered in the 2016 US election to boost Mr Trump's candidacy.

According to reports, after US officials were briefed of the alleged interference by Russia, Mr Trump then replaced his intelligence chief.

He erupted in anger at acting director of national intelligence (DNI) Joseph Maguire when he learned of the 13 February session with the House Intelligence Committee, The Washington Post and New York Times reported.

Mr Maguire's aide, Shelby Pierson, reportedly told politicians that Russia was once again meddling in the US election on Mr Trump's behalf.

Mr Trump complained that the Democrats would use the information against him, the reports said.

The president was also annoyed by the presence of Adam Schiff, the Democratic head of the investigation that led to Mr Trump being impeached for abuse of power and obstruction of Congress, according to the New York Times.

Mr Maguire had been a favourite to be nominated for the permanent DNI post but Mr Trump changed his mind about him, The Washington Post said, when he heard about the classified election security briefing.

The president berated Mr Maguire in an Oval Office showdown last week for the "disloyalty" of his staff, the Post reported, effectively thwarting his chances of becoming a permanent hire.

Mr Trump announced on Wednesday he was replacing Mr Maguire with Richard Grenell, 53, the ambassador to Germany and a Trump loyalist.

The Kremlin said the allegations of interference are false and the result of paranoia.

"These are more paranoid announcements which, to our regret, will multiply as we get closer to the (US) election," Kremlin spokesman Dmitry Peskov told reporters.

"They have nothing to do with the truth."

Mr Trump was impeached in December over accusations that he tried to coerce ally Ukraine into helping him win the 2020 election, withholding military aid considered vital to the former Soviet republic in its war with Russia.

Democratic congressman Bennie Thompson said that by firing Mr Maguire over the briefing "the president is not only refusing to defend against foreign interference, he's inviting it."

Mr Schiff tweeted that if Mr Trump was interfering in the sharing of intelligence information with Congress, it appeared that he was "again jeopardising our efforts to stop foreign meddling." 

US intelligence concluded that Russia interfered in the 2016 election, especially through manipulation of social media, to support Mr Trump.

Mr Trump has however repeatedly called it a "Russia hoax" and has instead promoted a debunked conspiracy theory that Ukraine intervened instead.

He has been at odds with much of the national security establishment since he took office and claims, without providing evidence, that a "deep state" is working against him.

Since he was acquitted by the Republican-led Senate, he has been purging the Justice Department, National Security Council and Pentagon of staff he considers disloyal.

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