Former national security adviser John Bolton has accused US President Donald Trump of lying more than once while being in office, according to a promotional clip of an interview with ABC News.
"Is the President lying?" ABC's host, Martha Raddatz, asked.
"Yes, he is. And it's not the first time," Bolton replied, according to the preview.
The interview, framed as a conversation with “the person the president doesn't want you to hear from,” is set to air on Sunday.
The clip also shows Bolton saying that he has not spoken to Trump since his resignation in September and doubts he ever will again.
This comes as Bolton and Trump have locked horns over Bolton's upcoming memoir, which is set to be released next week.
On Tuesday, the Trump administration announced that is has filed a lawsuit to prevent publication of the book it said contains classified information.
The White House National Security Council "has determined that the manuscript in its present form contains certain passages - some up to several paragraphs in length - that contain classified national security information," the lawsuit said.
Publication of the book "would cause irreparable harm, because the disclosure of instances of classified information in the manuscript reasonably could be expected to cause serious damage, or exceptionally grave damage, to the national security of the United States," according to the lawsuit.
In a part of his book, obtained by the US media, Bolton levels a stunning accusation against Trump, claiming that the Republican president had asked his Chinese counterpart, Xi Jinping, to help him win re-election.
Trump fired Bolton last September after roughly 17 months as national security adviser.
Trump said on Monday that Bolton knows he has classified information in his book, and that he had not completed a clearing process required for any book written by former government officials who had access to sensitive information.