05/03/2017 13:42 GMT | Updated 05/03/2017 15:24 GMT

Donald Trump Accuses Barack Obama Of 'Tapping' Phones, But Fails To Provide Evidence

Trump's tweets were so unexpected, aides were caught off guard.

Donald Trump appears to be sticking by his accusation that his predecessor Barack Obamawiretapped his phones in the late stages of last year’s election.

The 45th US President hit out at the 44th on Saturday, alleging, without any evidence, that Obama “had my ‘wires tapped’ in Trump Tower”. Obama has denied the claims.

But in a series of fresh tweets on Sunday, Trump didn’t acknowledge widespread calls for evidence from politicians in the US and the world’s media.

UPDATE: The White House has now called on Congress to investigate the claims.

Story continues below.

Sunday’s batch of early morning missives ignored the explosive nature of the allegations made a day previously.

“Terrible! Just found out that Obama had my ‘wires tapped’ in Trump Tower just before victory. Nothing found. This is McCarthyism!,” Trump wrote on Saturday.

The allegations were reportedly so unexpected, aides to the president at the West Palm beach resort where he takes weekends, were caught completely off guard.

One said it was unclear what Trump was referring to, Reuters reported.

Members of Congress said Trump’s accusations require investigation or explanation.

Carlos Barria / Reuters
Members of Congress have asked for evidence after Trump's explosive Obama accusations

But since making the claims about Obama, neither Trump nor the White House have responded to questions about where the president obtained his information.

Obama spokesman Kevin Lewis said it had been a “cardinal rule” of the Obama administration that no White House official ever interfered with any independent investigation led by the Department of Justice.

Lewis said in a statement: “Neither President Obama nor any White House official ever ordered surveillance on any U.S. citizen. Any suggestion otherwise is simply false.”

Jonathan Ernst / Reuters
Trump has spent part of the weekend at his resort near West Palm Beach, Florida

Trump has in the past tweeted about unsubstantiated and provocative reports he reads on blogs or conservative websites, the Associated Press reported.

But even among Trump’s timeline of vitriol, the tweets stand out.

The remarkable tussle between the current and former presidents is the latest twist in a controversy over ties between Trump associates and Russia that has dogged the early days of his presidency.

Jonathan Ernst / Reuters
Trump held a rally on Saturday near to West Palm Beach and his Mar-a-Lago resort

US intelligence agencies concluded last year that Russia hacked and leaked Democratic emails during the election campaign as part of an effort to tilt the vote in Trump’s favour. The Kremlin has denied the allegations.

Trump has accused officials in Obama’s administration of trying to discredit him with questions about Russia contacts, Reuters reported.

Trump said the alleged wiretapping took place in his Trump Tower office and apartment building in New York, but there was “nothing found.”

The White House did not respond to a request to elaborate on Trump’s accusations.

Obama’s statement did not address the possibility that a wiretap of the Trump campaign could have been ordered by Justice Department officials.

Trump’s allegations may be related to anonymously sourced reports in British media and blogs, and on conservative-leaning U.S. websites, including Breitbart News - already linked to Trump through former executive and now White House advisor Steve Bannon.

Those reports claimed that US officials had obtained a warrant under the Foreign Intelligence Surveillance Act to review contacts between computers at a Russian bank and Trump’s New York headquarters.

Rising scrutiny of Russia ties

This latest furore comes amid rising scrutiny of Trump’s campaign ties to Russia.

Trump has been trailed for months by questions about his campaign’s ties to Russia.

The questions have been compounded by U.S. intelligence agencies’ assessment that Russia interfered with the election to help Trump triumph over Hillary Clinton, along with disclosures about his aides’ contacts with a Russian official.

Those disclosures have already cost retired Gen. Michael Flynn his job as national security adviser and prompted calls from Democrats for Attorney General Jeff Sessions to resign.

On Thursday, Sessions recused himself from the FBI probe after acknowledging he did not disclose his campaign-season contacts with Russia’s ambassador to the United States when asked during his confirmation proceedings. Sessions, a U.S. senator at the time, was Trump’s earliest Senate supporter.

The Sessions revelations deepened the president’s anger over what he sees as his team’s inability to get ahead of the Russia allegations.

In the Oval Office meeting Friday shortly before departing for Florida, he angrily told senior advisers that what had the potential to be a good week following his address to Congress had been overtaken by the Russia controversy, according to a White House official who insisted on anonymity in order to discuss the private meeting.