U.S. President Donald Trump on Tuesday called former White House aide Omarosa Manigault Newman a "dog" and his campaign took legal action against her as the two former reality TV stars escalated their public feud.

The spat came as Manigault Newman, a former contestant on Trump's "The Apprentice," publicly released more recordings from her time in Trump's orbit as she promoted her tell-all book, "Unhinged," describing her year at the White House. She was fired in December.

In the book, she accused Trump of making derogatory statements about African-Americans, Filipinos and other minorities, as well as exhibiting "forgetfulness and frustration."