US President Donald Trump has accused Barack Obama of tapping his phones at Trump Tower in a flurry of tweets early Saturday morning.

Trump tweeted that the former president had been spying on him in October, a month before his election victory, reported Daily Mail.

'Terrible! Just found out that Obama had my 'wires tapped' in Trump Tower just before the victory. Nothing found. This is McCarthyism!'

McCarthyism, which the president used in his first tweet, is the practice of making accusations of subversion or treason without proper regard for evidence.

Trump started tweeting shortly after 3.30am ET and posed the question: 'Is it legal for a sitting President to be 'wire tapping' a race for president prior to an election?'

In another tweet Trump said it was a 'new low' for the former president and compared it to 'Nixon/Watergate'.

Trump also linked Obama to Attorney General Jeff Sessions's meetings last year with Russia's US ambassador, Sergey Kislyak.

'The first meeting Jeff Sessions had with the Russian Amb was set up by the Obama Administration under education program for 100 Ambs,' he tweeted.

Trump's team has sought to push back over its connections to Russian officials by pointing out instances of Democrats meeting with Kislyak.

A former senior intelligence official told The Washington Post that 'it's highly unlikely there was a wiretap'.

The president, who is currently vacationing at his private Mar-a-Lago estate, did not provide any additional evidence to back up his claims.