- Video report by ITV News Washington Correspondent Robert Moore
A spokesman for Barack Obama has rejected Donald Trump’s claim that the White House ordered a tap on his phone lines before the presidential election.
Mr Trump accused his predecessor having his “wires tapped” in a “new low” that he said could be the biggest political scandal since Watergate.
A spokesman for Mr Obama said the explosive allegations made by the new president on Twitter were “simply false”.
Referring to the allegations, Mr Trump suggested a "good lawyer could make a great case".
He also drew parallels with the 1970s Watergate scandal that forced President Richard Nixon to resign, referring to Mr Obama a "bad (or sick) guy".
One of his Mr Obama's aides, Ben Rhodes, had also refuted the claims on Twitter.
Mr Rhodes, who was foreign policy advisor and speechwriter, said: "No president can order a wiretap. Those restrictions were put in place to protect citizens from people like you."
He added: "Dear pundits who lauded his speech. Is it still 'presidential' to call your dignified predecessor 'Bad (or sick) guy!'"
- How is wire-tapping authorised in the US?
Wire-tapping is strictly controlled worldwide, and in the case of the US, can only be permitted and authorised by a court.
Under the Foreign Intelligence Surveillance Act (FISA), federal intelligence agencies can ask for approval for wiretaps from the US FISA court, for which proceedings are secret.
It was revealed in January that intelligence agencies had obtained a FISA warrant in October.
The extraordinary claim comes after a week of trouble for the White House, which saw Trump fighting for his Attorney General Jeff Sessions as it was revealed he had misled the Senate about ties with Russia.