A spokesman for Barack Obama has rejected claims from US President Donald Trump that the former president had wiretapped him in October during the late stages of the presidential election campaign.
"Neither President Obama nor any White House official ever ordered surveillance on any US citizen. Any suggestion otherwise is simply false," Obama spokesman Kevin Lewis said in a statement on Saturday.
Trump had suggested Obama had improperly tapped his phones, without citing evidence, in a series of tweets on Saturday morning.
"How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!," Trump said in a series of tweets.
"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!"
Lewis also said that "a cardinal rule of the Obama Administration was that no White House official ever interfered with any independent investigation led by the Department of Justice."
The statement raised the possibility that a wiretap of the Trump campaign could have been ordered by Justice Department officials.
The White House did not respond to a request to elaborate on Trump's accusations.
A Trump spokeswoman said the Republican president is "having meetings, making phone calls and hitting balls" at his golf course in West Palm Beach.
Earlier, former Obama adviser Ben Rhodes strongly denied Trump's allegations.
"No president can order a wiretap. Those restrictions were put in place to protect citizens from people like you," Rhodes wrote on Twitter.
In one of the Tweets, Trump said the alleged wiretapping took place in his Trump Tower office and apartment building in New York, but there was "nothing found."
Trump's administration has come under pressure from Federal Bureau of Investigation and congressional investigations into contacts between some members of his campaign team and Russian officials during his campaign.
House Democratic Leader Nancy Pelosi ridiculed Trump's assertions. "The Deflector-in-Chief is at it again. An investigation by an independent commission is the only answer," she wrote on Twitter on Saturday.
Under US law, a federal court would have to have found probable cause that the target of the surveillance is an "agent of a foreign power" in order to approve a warrant authorising electronic surveillance of Trump Tower.
