President-elect Donald Trump's pick for a top national security position stepped down amid allegations that she had plagiarised significant portions of her book and other writings.

Conservative writer Monica Crowley was tapped to be the senior director of statregic communications at the National Security Council, but a scathing report from CNN's KFILE found that she had allegedly plagiarised passages in her 2012 book What the (Bleep) Just Happened.

Two days after that report, Politico uncovered similar issues of apparent plagiarism in her PhD dissertation.

"After much reflection, I have decided to remain in New York to pursue other opportunities and will not be taking a position in the incoming administration," Ms Crowley said in a statement to the Washington Times, the conservative blog to which she regularly contributes. "I greatly appreciate being asked to be a part of President-elect Trump's team and I will continue to enthusiastically support him and his agenda for American renewal."

Ms Crowley would have worked alongside incoming National Security Adviser, Gen Michael Flynn.

"The NSC will miss the opportunity to have Monica Crowley as part of our team," said Mr Flynn. "We wish her all the best in her future."

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HarperCollins, the publisher of Ms Crowley's book, announced that they would cease sales after learning of the plagiarism accusations.

"The book, which has reached the end of its natural sales cycle, will no longer be offered for purchase until such time as the author has the opportunity to source and revise the material," the publisher said.

Ms Crowley is the second person to decline a position in the incoming Trump administration.

Jason Miller was offered the role of communications director, but decided against taking it – an announcement that took the political press by surprise.