Rex Tillerson, the former secretary of state for the Trump administration, fired back at Nikki Haley over bombshell accusations she made that he had tried to undermine the president's agenda.

Contrary to Haley's claims, he told the New York Times on Monday that "at no time did I, nor to my direct knowledge did anyone else serving along with me, take any actions to undermine the president."

He also appeared to take a shot at Haley, who served as the U.S. ambassador to the United Nations for the Trump administration, by further claiming she was rarely present at meetings.

"Ambassador Haley was rarely a participant in my many meetings and is not in a position to know what I may or may not have said to the president," Tillerson said.

Haley made the accusations in new book, "With All Due Respect," according to the Washington Post. She included former White House chief of staff John Kelly among those undermining the president.

"Kelly and Tillerson confided in me that when they resisted the president, they weren't being insubordinate, they were trying to save the country," she wrote.

Haley said she resisted their efforts to have her join their resistance to the president from within his administration.

President Donald Trump unceremoniously fired Tillerson in March 2018 and replaced him with Mike Pompeo. He later called Tillerson "dumb as a rock," and "lazy as hell."

Here's more about Haley's accusations: