US President Donald Trump says a controversial memo attacking federal law enforcement written by congressional Republicans vindicates him in the investigation of Russian meddling in the 2016 US presidential election.

Trump's fervent embrace of the memo raised again the prospect that he may use it as justification to fire special counsel Robert Mueller, who is conducting the investigation, or Deputy Attorney General Rod Rosenstein, who oversees Mueller.

Tweeting from his resort in Palm Beach, Florida, Trump said the memo "totally vindicates" him but added "the Russian Witch Hunt goes on and on. Their (sic) was no Collusion and there was no Obstruction." He called the investigation "an American disgrace".

The White House said on Friday there would be no changes at the Justice Department as a result of the memo's conclusions.