Former presidential adviser Omarosa Manigault Newman says she secretly recorded conversations she had in the White House, including her sacking by chief of staff John Kelly in the high-security Situation Room.
The highly unusual admission on US television network NBC has drawn immediate fire from allies of the president and national security experts.
Parts of her conversation with Kelly were aired on Sunday when she appeared on Meet the Press to promote her new book, Unhinged, which will be released this week.
The Associated Press independently listened to the recording of the conversation between Manigault Newman and Kelly, which she said was one of many she'd surreptitiously recorded for her own protection.
In her book, Manigault Newman paints a damning picture of US President Donald Trump, including claiming without evidence that tapes exist of him using the N-word as he filmed his "The Apprentice" reality series, on which she co-starred.
Manigault Newman said in the book that she had not personally heard the recording. But she told Chuck Todd on Sunday that, after the book had closed, she was able to hear a recording of Trump during a trip to Los Angeles.
"I heard his voice as clear as you and I are sitting here," she said on the show.
But the other recording she discussed Sunday could prove equally explosive.
"Who in their right mind thinks it's appropriate to secretly record the White House chief of staff in the Situation Room?" tweeted Ronna McDaniel, chair of the Republican National Committee.
In the recording, which Manigault Newman quotes extensively in the book, Kelly can be heard saying that he wants to talk with Manigault Newman about leaving the White House.
"It's come to my attention over the last few months that there's been some pretty, in my opinion, significant integrity issues related to you," Kelly is heard saying, citing her use of government vehicles and "money issues and other things" that he compares to offences that could lead to a court martial in the military.
"If we make this a friendly departure ... you can look at your time here in the White House as a year of service to the nation and then you can go on without any type of difficulty in the future relative to your reputation," he goes on to tell Manigault Newman, adding that: "There are some serious legal issues that have been violated and you're open to some legal action that we hope, we think we can control."
Manigault Newman said she viewed the conversation as a "threat" and defended her decision to covertly record it and other White House conversations.
"If I didn't have these recordings, no one in America would believe me," she said.
The response from the White House was stinging.
"The very idea a staff member would sneak a recording device into the White House Situation Room, shows a blatant disregard for our national security - and then to brag about it on national television further proves the lack of character and integrity of this disgruntled former White House employee," press secretary Sarah Huckabee Sanders said in a statement.
The Situation Room is a Sensitive Compartmented Information Facility, or SCIF, where the nation's most consequential foreign policy decisions are made, and staff are not permitted to bring in mobile phones or other recording devices.
The White House had previously tried to discredit the book, while on Saturday Trump labelled Manigault Newman a "lowlife".