US PRESIDENT Donald Trump has accused former leader Barack Obama of ordering a wire tap on Trump Tower ahead of his election win.
Mr Trump made the explosive accusation in an early morning tweet on Saturday, comparing it to "McCarthyism" - Senator Joe McCarthy's campaign in the 1950s to root out alleged Communists and sympathisers.
He offered no evidence for his claims.
Mr Obama's spokesman said the accusation was "simply false" in response.
"Terrible!" the President said in his tweet. "Just found out that Obama had my 'wires tapped' in Trump Tower just before the victory. Nothing found. This is McCarthyism!"
A few minutes later he added: "Is it legal for a sitting President to be "wire tapping" a race for president prior to an election? Turned down by court earlier. A new low!"
Shortly afterwards he wrote: "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!"
In the explosive tirade Mr Trump went on to call the former leader a "bad (or sick) guy".
"How low has President Obama gone to tape (sic) my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!" he wrote in another tweet, referring to the political scandal that toppled president Richard Nixon in 1974.
There are also reports that The US Justice Department wiretapped journalists during Obama's terms as president.
Wire agency AP was targeted in one case, secretly obtaining two months of telephone records of reporters and editors and what the company's top executive described as a "massive and unprecedented intrusion" into how news organisations gather their news.
The records include a list of outgoing calls for the work and personal phone numbers of individual reporters and some AP offices in parts of the US. It is believed more than 100 journalists were targeted in the operation.
"There can be no possible justification for such an overbroad collection of the telephone communications of The Associated Press and its reporters," said AP president and CEO Gary Pruitt.
"These records potentially reveal communications with confidential sources across all of the newsgathering activities undertaken by the AP during a two-month period, provide a road map to AP's newsgathering operations and disclose information about AP's activities and operations that the government has no conceivable right to know."
Fox News is also reporting one of its journalists was investigated as a co-conspirator in a criminal spying case.
James Rosen, the company's chief Washington correspondent, was named "at the very least, either as an aider, abettor and/or co-conspirator" in a 2010 espionage case against State Department security adviser Stephen Jin-Woo Kim.
The FBI sought and obtained a warrant to seize all of Rosen's correspondence with Kim, and an additional two days' worth of Rosen's personal email, the Washington Post reported.
The bureau also obtained Rosen's phone records and used security badge records to track his movements to and from the State Department.
Fox News issued a sharply worded statement on Monday calling the episode "downright chilling".
A spokesman for Mr Obama denied the claims, saying the former president never ordered surveillance on any US citizen.
"President Obama nor any White House official ever ordered surveillance on any US citizen," spokesman Kevin Lewis said in a statement.
"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," he said.
Meanwhile, top Obama adviser Ben Rhodes issued a searing response on Twitter. "No President can order a wiretap. Those restrictions were put in place to protect citizens from people like you," Mr Rhodes wrote.
Mr Trump offered no explanation for the basis for his claims. The US president has become known for his outlandish claims on Twitter often backed by no evidence.
He was a strong advocate of the "birthed" conspiracy theory, which claimed that Mr Obama was not born in the US.
Citing anonymous sources Mr Trump repeatedly alleged that Mr Obama's birth certificate was a "fraud", before finally admitting his claims were false in September last year.
In the same flurry of early morning tweets the US leader sought to defend Jeff Sessions, the US lawyer general facing scrutiny over his meeting with the Russian ambassador to Washington during the 2016 presidential election campaign.
He tweeted: "The first meeting Jeff Sessions had with the Russian Amb was set up by the Obama Administration under education program for 100 Ambs ..." .
He added: "Just out: The same Russian Ambassador that met Jeff Sessions visited the Obama White House 22 times, and 4 times last year alone."
The Trump administration has been under pressure for its ties to Russia since the Kremlin was accused of hacking the US election in favour of Mr Trump.
Although it was not clear on what Mr Trump was basing his claims of wire-tapping there were reports at the time of the election that the FBI was investigating the Trump campaign's Russia links.
The news website Heat Street claimed last November that two separate sources with links to the counterintelligence community said that the FBI sought, and was granted, a court warrant in October, giving them permission to examine the activities of "US persons" in Donald Trump's campaign with ties to Russia.
In a report published the day before the election the site said that the first request, which named Mr Trump, was denied back in June, but the second was drawn more narrowly and was granted in October after evidence was presented of a server, possibly related to the Trump campaign, and its alleged links to two Russian banks.
Last month Mr Trump's national security adviser, Michael Flynn, was forced to resign over his contact with Sergey Kislyak, the Russian ambassador, and misleading statements about it to the press and the US vice-president, Mike Pence.
This week it was revealed that Mr Sessions had two meetings with Mr Kislyak last year that he failed to disclose to senators in his confirmation hearing.
Mr Sessions said on Friday he would recuse himself from a probe into Russian interference in the 2016 election despite backing from Mr Trump, who called the controversy "a total witch hunt".
Also on Friday Mr Trump tried to hit back at his political opponents by citing their alleged ties to Russia.
The US president tweeted a 2003 photo of US Senate Minority Leader Chuck Schumer with Russian President Vladimir Putin. Under the photo he wrote: "We should start an immediate investigation into @SenSchumer and his ties to Russia and Putin. A total hypocrite!"
Mr Schumer, who was among a number of Democrats who called this week for Mr Sessions to resign, quickly retweeted the message adding: "Happily talk re: my contact w Mr. Putin & his associates, took place in '03 in full view of press & public under oath. Would you & your team?"
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