Former US President Barack Obama has flatly rejected a claim by President Donald Trump that he - Obama - tapped Trump’s phone in the run-up to November’s election.
Mr Trump made the sensational claim over twitter in the early hours of this morning, and called Mr Obama a "bad (or sick) guy", using his favoured medium of twitter and not citing any evidence or source for the claim.
Terrible! Just found out that Obama had my "wires tapped" in Trump Tower just before the victory. Nothing found. This is McCarthyism!
— Donald J. Trump (@realDonaldTrump) March 4, 2017
Barack Obama has now issued a reply through spokesman Kevin Lewis, which amounts to a flat rejection of the claim.
Kevin Lewis said a "cardinal rule" of the Obama administration was that no White House official ever interfered in any Justice Department investigations, which are supposed to be conducted free of political influence.
"As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any US citizen," Lewis said, adding that "any suggestion otherwise is simply false".
The White House did not immediately reply to inquiries about what prompted the president's tweets.
Trump compared the alleged activity to behaviour involving president Richard Nixon and the bugging of his political opponents.
Earlier, former Obama adviser Ben Rhodes responded to Mr Trump’s tweet by saying “No President can order a wiretap.”
No President can order a wiretap. Those restrictions were put in place to protect citizens from people like you. https://t.co/lEVscjkzSw
— Ben Rhodes (@brhodes) March 4, 2017
Trump's tweets came days after disclosures that Attorney General Jeff Sessions, during his Senate confirmation hearing, did not disclose his own campaign season contacts with Russia's ambassador to the United States.
Sessions, a US senator at the time, was Trump's earliest Senate supporter.
Trump's opening tweet on Saturday mentioned Sessions and claimed the first meeting Sessions had with the Russian diplomat was "set up by the Obama Administration under education program for 100 Ambs."
US intelligence agencies have concluded that Russia interfered in the campaign with the goal of helping elect Trump over Democrat Hillary Clinton, findings that Trump has dismissed.
The FBI has investigated Trump associates' ties to Russian officials. Congress is also investigating.
Trump has blamed Democrats for leaks of information about the investigation and the contacts.
It was unclear what prompted Trump's new charge. The president often tweets about reports he reads on blogs and conservative-leaning websites.
After tweeting Saturday about Obama, as well as about Arnold Schwarzenegger's decision to leave The New Celebrity Apprentice, Trump went to his golf club in nearby West Palm Beach.