Donald Trump’s pick for senior director of strategic communications for the National Security Council said president Barack Obama lied about his race and it was "the biggest con she had ever seen".

Fox News’ host Monica Crowley has been selected by the transition team, and will serve under retired army general Michael Flynn, who said fear of Muslims was "rational" and that Islam was a "cancer".

Ms Crowley will also join previous Fox News employee KT McFarland, who was appointed deputy national security adviser. Ms McFarland said that not discriminating against Muslims is "getting us killed" and there is a "war on against western civilisation".

Ms Crowley worked at Fox news since 1998 as a "political and international affairs analyst", according to her bio, and was foreign policy assistant to former president Richard Nixon.

When she guest hosted Laura Ingraham’s radio show in June 2008, she accused Mr Obama of lying that he was an African American.

Referring to a widelt debunked argument which she said she had not verified or researched, she agreed with a caller to the show that the president was only "6 per cent African American".

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"And yet, this guy is campaigning as black and painting anybody who dares to criticize him as a racist. I mean that is—it is the biggest con I think I've ever seen," she said.

She was citing the so-called investigation of Kenneth Lamb, who said he went to Kenya and studied government records, "proving" that Mr Obama was an Arab-American.

'All of Donald Trump's political activity stems back to 'racist birther lie'

Mr Obama’s opponents, who often cite his three names to draw attention to his mixed race background, rarely cite the three names of Hillary Rodham Clinton or Donald John Trump.

"Well Barack Hussein Obama can certainly go from being a black panther to a Norman Rockwell painting in the blink of an eye, can't he?" asked Ms Crowley on the radio show.

The president was born in Hawaii. His mother was a white American, his father a black Kenyan. Yet his critics, including Mr Trump, espoused a conspiracy “birther” theory that he was born in Africa. Mr Trump only formally denounced the conspiracy theory two months before the election, and incorrectly accused Ms Clinton of starting the rumour instead.

Ms Crowley said the birth certificate issue plaguing Mr Obama was worth considering given his polices were "un-American" and it "feeds into this idea that somehow, fair or not, Obama is not one of us."

Mr Trump’s spokesperson was not immediately available for comment.