Never worked for Russia, says Trump

US President Donald Trump on Monday dismissed reports that he ever "worked" for Russia and said that any such report is just a "hoax".

"I never worked for Russia and you know that answer better than anybody. I never worked for Russia," Trump said.

"Not only did I never work for Russia, I think it's a disgrace that you even ask that question because it's a whole big fat hoax. It's just a hoax," he said amid news reports that the FBI had opened an investigation over whether Trump acted on Russia's behalf after he sacked the agency's then director James Comey in 2017.

Another report alleged that Trump does not share the details of his talks with Russian President Vladimir Putin. The White House has described those reports as ridiculous.

Earlier on Twitter, Trump attacked such reports as fake.

"The Fake News gets crazier and more dishonest every single day. Amazing to watch as certain people covering me, and the tremendous success of this administration, have truly gone MAD! Their Fake reporting creates anger and disunity. Take two weeks off and come back rested. Chill !," Trump wrote.