Donald Trump has ramped up his attacks on journalists, echoing Chairman Mao Zedong and other dictators by branding a large section of the mainstream media "enemy of the people".

After a combative press conference on Thursday, in which he railed at "fake news", bullied reporters and dismissed facts, the president took to Twitter on Friday to continue his assault on the press.

"The FAKE NEWS media (failing @nytimes, @NBCNews, @ABC, @CBS, @CNN) is not my enemy, it is the enemy of the American People!," he declared.