Trump attorney Charles Harder has sent a letter to Bannon, saying the former Trump aide violated confidentiality agreements by speaking with reporter Michael Wolff for a book. The letter demands Bannon "cease and desist" any further disclosure of confidential information.
White House Press Secretary Sarah Huckabee Sanders complained Wednesday the book contained "outrageous" and "completely false claims against the president, his administration and his family."
In the book, Bannon is quoted as describing a June 2016 meeting at Trump Tower between Donald Trump Jr., Trump campaign aides and a Russian lawyer as "treasonous."
Bannon did not immediately respond to a request for comment. ABC News first reported the letter from Harder.
The Associated Press contributed to this report.
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