Donald Trump accuses Barack Obama of 'wire-tapping' office during election.

US President Donald Trump has accused former president Barack Obama of “wire-tapping” his office phones during the 2016 election campaign.

Mr Trump made the accusation in a series of tweets from his personal Twitter account on Saturday morning (US time).

“Terrible! Just found out that Obama had my ‘wires tapped’ in Trump Tower just before the victory. Nothing found. This is McCarthyism!” he tweeted.

He then followed it with a further series of tweets: “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!

“How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!”

There was no information provided to substantiate Mr Trump’s claims, and it was not clear on what he was basing them — although on Thursday, a conservative radio host made claims about alleged steps taken by the Obama administration to influence the election.

The comments were followed yesterday by far right-wing news outlet Breitbart, which published an article claiming the Obama administration eavesdropped on the Trump campaign.

During his series of tweets, Mr Trump also noted that Russian ambassador Sergei Kislyak had visited the White House “22 times, and 4 times last year alone”.

There have been calls for current Attorney-General Jeff Sessions to resign after it was revealed that he failed to disclose two conversations he had with Mr Kislyak during the presidential campaign.

This post originally appeared on ABC News.