Donald Trump’s Twitter messages accusing Barack Obama of wiretapping his building are intended “to distract from a scandal,” the former President's spokesman has claimed.

“The bigger the scandal, the more outrageous the tweet,” said Josh Earnest, who worked as Mr Obama’s Press Secretary for three years.

Last week, headlines about Attorney General Jeff Sessions and his contact with Russian officials dominated the media. But since Mr Trump’s Twitter tirade – made without evidence – the news agenda has shifted to the surveillance allegations.

The White House has demanded an investigation into the “Watergate” level allegations as part of any enquiry into Russian connections with the Trump administration. Mr Trump has maintained his support for Mr Sessions.

Mr Earnest told ABC News: “We know exactly why President Trump tweeted what he tweeted. Because there is one page in the Trump White House crisis management playbook. And that is simply to tweet or say something outrageous to distract from a scandal.

“And the bigger the scandal, the more outrageous the tweet.”

Former director of national intelligence denies there was a 'wiretap' at Trump Tower

Mr Earnest did not deny that surveillance may have occurred, but said the President cannot “unilaterally order” the wiretapping of a US citizen.

For surveillance to have taken place, Mr Earnest said, FBI investigators would have needed probable cause as part of a criminal or counterintelligence operation. A judge would need to approve the case before any such operation could take place, he added.

Mr Obama denied the allegations at the weekend as “simply false” but stopped short of saying outright that there was no surveillance of Trump Tower.

“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,” said a statement issued by Kevin Lewis, Mr Obama’s spokesperson.

“As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any US citizen. Any suggestion otherwise is simply false.”

Mr Earnest said he could “categorically deny” that the Obama administration had ever tried to influence an FBI investigation. He distanced himself from talking in more detail about security operations in the previous administration as he said it was not something he was regularly privy to.

Meanwhile, the former director of national intelligence, James Clapper, denied surveillance was used against Mr Trump or his campaign.

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Mr Clapper was still in his post at the time of the allegations.

He told NBC: "There was no such wire-tap activity mounted against the president-elect at the time, as a candidate, or against his campaign."

Mr Clapper said he would have been aware of a "court order on something like this. Absolutely, I can deny it".