Trump accuses Obama of tapping his phone
President Trump tweeted early on Saturday: "Terrible! Just found out that Obama had my "wires tapped" in Trump Tower just before the victory. Nothing found. This is McCarthyism!"
He went on to say that a court had earlier denied a wiretap request.
The US president has given no details to back up the claim - or suggested which court order he was referring to.
Media reports in the past few weeks have suggested the FBI had sought a warrant from the foreign intelligence surveillance court (Fisa) last summer in order to monitor members of the Trump team suspected of irregular contacts with Russian officials.
The warrant was first turned down but then approved in October, according to the media reports.
There has been no official confirmation and it is also not clear if this evolved into a full investigation.
Source: bbc.com