WASHINGTON (BLOOMBERG) - Former White House aide Omarosa Manigault Newman said President Donald Trump should be impeached, the latest escalation in an ongoing feud between two former reality TV stars.

"At this point, yes," she said when asked if her former boss should be removed from office, during an interview on Monday (Aug 13) on MSNBC's Hardball.

Manigault Newman, who has questioned Trump's mental stability and accused him of being a racist, said that she has several audio tapes from her time in the White House that she is willing to provide to Special Counsel Robert Mueller.

"If his office calls again, anything they want, I'll share," she said, indicating that she had already been in touch with Mueller's team as part of its investigation into Russian interference in the 2016 election.

Trump lashed out at his former aide, attacking her intelligence after she released a recording of a call with the president in which he appeared not to know she'd been let go from her White House job the day before.

"Wacky Omarosa, who got fired 3 times on the Apprentice, now got fired for the last time," Trump said on Twitter on Monday. "She never made it, never will. She begged me for a job, tears in her eyes, I said Ok. People in the White House hated her. She was vicious, but not smart."

Later, Trump said she had "fully signed" a non-disclosure agreement. He didn't elaborate. Manigault Newman said she had declined to sign such an agreement.

She is the first former high-ranking official from Trump's White House to call for his impeachment.

On Sunday, Manigault Newman released a tape she said she'd secretly made of her 2017 firing by Chief of Staff John Kelly.

Trump aides have sought to aggressively counter her claims, which coincide with the release of her tell-all book.

White House Press Secretary Sarah Huckabee Sanders called her "a disgruntled former White House employee" in a statement on Sunday.

In a phone call that Manigault Newman claims to have recorded with Trump after Kelly fired her, aired Monday on NBC's Today, a voice that sounds like the president's asks: "Omarosa what's going on? I just saw on the news that you're thinking about leaving. What happened?"

After Manigault Newman told Trump she'd been fired, he responded: "No, nobody even told me about it. You know they run a big operation, but I didn't know it."

The White House has not disputed the authenticity of Manigault Newman's recordings.

Trump's attorney Rudy Giuliani said on Fox News's Fox & Friends on Monday that the thinks Manigault Newman violated the law by taping Trump and other White House officials.

"The president makes the decisions in this White House," White House Deputy Press Secretary Hogan Gidley said on Fox News. "I'm not going to get into the tick-tock of who knew what and when."

Gidley said taping the meetings was an ethical breach of private conversations, and said Manigault Newman has "zero credibility".

In another tweet on Monday, Trump disparaged Manigault Newman and said he wanted to ensure the "Fake News Media" doesn't lend her story an air of plausibility.

"While I know it's 'not presidential' to take on a lowlife like Omarosa, and while I would rather not be doing so, this is a modern day form of communication," he said in the post.

In Unhinged: An Insider's Account Of The Trump White House, Manigault Newman, one of relatively few black people in the White House, accuses the president of having used racial slurs on the set of The Apprentice reality TV show, which was broadcast NBC.

Manigault-Newman told NBC News on Monday that the title of her book was aimed directly at Trump. She said Kelly was in charge of the White House.

"John Kelly is running this White House and Donald Trump has no clue what's going on," she said. "He's being puppeted, and that's very dangerous for this nation."

"He absolutely has an issue with the truth, and sometimes he battles with reality," she said of Trump.

During the taped call, Trump is heard telling Manigault Newman of her firing, "Goddammit. I don't love you leaving at all. Nobody even told me about it."

In a follow-up tweet on Monday morning, Trump claimed that Manigault Newman frequently missed work commitments.

"Nasty to people & would constantly miss meetings & work. When Gen. Kelly came on board he told me she was a loser & nothing but problems. I told him to try working it out, if possible, because she only said GREAT things about me - until she got fired!" Trump tweeted.

During the interview on Today, Manigault Newman claimed that during her firing she was locked in the White House situation room and denied access to counsel, which she said amounted to "false imprisonment".

The Today appearance became combative at times, with the former aide saying it went beyond the agreed-upon seven-minute time frame.