Nikki Haley, Donald Trump's former UN ambassador, alleges in her upcoming memoir that two administration officials who were ultimately pushed out by Mr Trump once tried to get her to join them in opposing some of his policies.

In "With All Due Respect," Ms Haley said then-Secretary of State Rex Tillerson and then-White House chief of staff John Kelly told her that they were trying to "save the country."

Ms Haley wrote that she was "shocked" by the request, made during a closed-door meeting, and thought they were only trying to put their own imprint on his policies.

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

"It was their decisions, not the president's, that were in the best interests of America, they said. The president didn't know what he was doing...Tillerson went on to tell me the reason he resisted the president's decisions was because, if he didn't, people would die."

The former South Carolina governor said the meeting lasted more than an hour and that they never raised the issue to her again.

Ms Haley's book comes out Tuesday.

"Instead of saying that to me, they should've been saying that to the president, not asking me to join them on their sidebar plan," she wrote.