DONALD Trump's allegation that his predecessor ordered his phone to be tapped is "simply false", Barack Obama's spokesman says.

In an astonishing salvo of early morning tweets, the firebrand President claimed his predecessor had bugged his phones during the "very sacred election process", slamming the allegations as a "Nixon/Watergate" scandal.

Trump, who started the Twitter rant at 5:30am US eastern time, branded the claims a "new low" before appearing to call Obama a "bad (or sick) guy".

But Obama has strongly denied the allegations.

His spokesman Kevin Lewis said: "President Obama nor any White House official ever ordered surveillance on any US citizen." 

The property tycoon turned politician wrote: "How low has President Obama gone to tap my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!"