President Donald Trump on Saturday accused his predecessor Barack Obama of "tapping" his phone during last year's White House campaign, without providing evidence of the explosive charge.

"I'd bet a good lawyer could make a great case out of the fact that President Obama was tapping my phones in October, just prior to Election!" Trump wrote on Twitter.

"How low has President Obama gone to tapp (sic) my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!," he wrote in another tweet.