Donald Trump believed there was Australian conspiracy against him - Omarosa Manigault Newman

One of Donald Trump's former top advisers has revealed the US President at one stage believed there was an Australian conspiracy against him.

In an interview with 60 Minutes, Omarosa Manigault Newman - who also competed on Trump's The Apprentice - discussed a now-infamous phone call between Trump and then-Australian Prime Minister Malcolm Turnbull.

In the January 2017 phone conversation, Trump reportedly scolded Turnbull over a previous agreement between the United States and Australia where the US would take 1250 refugees from an Australian detention centre. Turnbull stood up to him and reminded Trump of the US commitment.

Manigault Newman said the phone call left Trump "ranting" for days.

"The President's reaction to that call was just pretty shocking for us all," she told 60 Minutes.

"He was ranting and ranting. He thought that Turnbull had set him up.

"He was into name calling and there was some profanities. He described it as the worst call of all the leaders that he had in those early days."

According to Manigault Newman, Trump believed there was a conspiracy against him by the "Australian establishment", especially after a transcript of the phone call was leaked.

"He was so suspicious that the Australian establishment was out to get him. That this was all part of some massive conspiracy to make him look bad," she told 60 Minutes.

She believes Trump's outburst was partially motivated by the fact Turnbull stood up to him - something Trump did not like.

"Anyone that pushes back, that stands up to him, he immediately sees them as an adversary, and that's what happened. Australia stood up to Trump."

Manigault Newman said advisers in the White House were concerned about the implications of the phone call on US-Australia relations.

She was named as the Trump's campaigns Director of African-American outreach in 2016 and moved into an advisory role when Trump became President. However, she left the role in 2017 after differences with the administration.

The 60 Minutes episode also included an interview with Anthony Scaramucci - once the White House director of communications - who said Trump is a "full-blown lunatic".

"We're in a horror movie right now where people are afraid."

Newshub.