AN infuriated Donald Trump continued his attack on ousted aide Omarosa Manigault Newman on Tuesday by praising chief of staff John Kelly for "quickly firing that dog!"

"When you give a crazed, crying low-life a break, and give her a job at the White House, I guess it just didn't work out. Good work by General Kelly for quickly firing that dog!" Mr Trump tweeted.

Now, the Trump campaign has launched legal action against Manigault Newman saying she has breached a confidentiality agreement signed in 2016.

"Donald J Trump for President Inc has filed an arbitration against Omarosa Manigault Newman, with the American Arbitration Assocation in New York City for breach of her 2016 confidentiality agreement with the Trump campaign," a Trump campaign officials told Fox News in a statement.

"President Trump is well-known for giving people opportunities to advance in their careers and lives over the decades, but wrong is wrong, and a direct violation of an agreement must be addressed and the violator must be held accountable."

In arbitration, which both sides agreed to in the nondisclosure agreement, each agree to allow an arbitrator, often a retired judge, to hold a hearing.

The arbitrator, after hearing evidence, can dismiss the charge of slap her with a fine, which could be millions of dollars.

The US President's verbal lashing comes after he claimed late on Monday that no video exists of him uttering a racial slur, describing himself as a "true champion of civil rights", reports the New York Post.

Mr Trump denied the claim saying, "I don't have that word in my vocabulary, and never have".

Mr Trump's latest Twitter rant came after US television network, CBS, aired new audio, provided by Manigault Newman, of a 2016 conference call between top Trump staffers that supported some of her claims about the possible tape.

Nothing in the conference call recording suggests that an 'n-word' tape exists. It does, however, show Trump spokeswoman Katrina Pierson telling colleagues that she thinks it did - and discussing how to "spin it".

Ms Pierson, in an interview with Fox News, denied the conference call audio existed.

"That did not happen," Ms Pierson said. "It sounds like she's writing a script for a movie."

Manigault Newman, the White House's former liaison to black voters, reportedly writes in her new book, Unhinged, that she'd heard that tapes of Mr Trump using the 'n-word' existed. On Sunday, she said she had listened to one after the book went to print.

Earlier, Mr Trump belittled Manigault Newman as "wacky", "deranged" and "not smart" after his former co-star revealed her recording of a phone conversation with him.

The messy clash touched on a variety of sensitive issues in the White House, including a lack of racial diversity among senior officials, security in the executive mansion, a culture that some there feel borders on paranoia and the extraordinary measures used to muzzle ex-employees.

In an unusual admission, Mr Trump noted that the public sparring was perhaps beneath a person in his position, tweeting that he knew it was "not presidential" to take on "a low-life like Omarosa".

But he added: "This is a modern day form of communication and I know the Fake News Media will be working overtime to make even Wacky Omarosa look legitimate as possible. Sorry!"

- with the New York Post