Donald Trump has called Omarosa Manigault Newman “a lowlife” in his first public response to the former White House aide’s tell-all book.

In excerpts from the book entitled 'Unhinged', Manigault Newman claimed the president had used the “N-word” repeatedly, and also used racial slurs to refer to George Conway, the half-Filipino husband of the top White House aide Kellyanne Conway.

Manigault Newman, who had previously appeared with Trump on his reality television show The Apprentice, also said in the book that she believed he was “a racist, a bigot and a misogynist”.

The remarks were a break with comments made during the campaign when the former reality television celebrity vowed that those who had criticized Trump would bend the knee to him. “Every critic, every detractor, will have to bow down to President Trump,” Manigault Newman said in an interview with PBS in 2016.

Asked about the allegations at a photo-op with the group Bikers for Trump on Saturday in Bedminster, New Jersey, the president said: “Lowlife ... She’s a lowlife.”

Manigault Newman was dismissed from the White House in December, 2017. Sources close to her say she had long been uncomfortable defending the Trump administration as the most prominent African American woman in the White House.

On Friday, the White House press secretary, Sarah Sanders, issued a statement on Manigault Newman's new book, saying it was “riddled with lies” and condemning Manigault Newman for not praising Trump.