Trump threatens to cancel press briefings

US President Donald Trump has threatened to cancel "all future" White House press briefings.

"As a very active president with lots of things happening, it is not possible for my surrogates to stand at podium with perfect accuracy!" Trump wrote on Twitter on Friday.

"Maybe the best thing to do would be to cancel all future 'press briefings' and hand out written responses for the sake of accuracy???"

The president's Twitter postings come as the White House finds itself under fire for offering contradicting explanations as to why Trump fired FBI director James Comey on Tuesday.