The federal government's ethics watchdog warned President Donald Trump's transition team last fall about its "unprecedented" and risky approach to staffing the cabinet, according to new emails obtained by NBC News.

Walter Shaub, Director of the Office of Government Ethics (OGE) who has clashed with Trump's administration, wrote to the then-president-elect's top lawyer on Saturday, Nov. 19, with a warning about "imminent" cabinet appointments.

"I am not sure whether you are aware that announcing the cabinet without first coordinating with OGE is unprecedented," he wrote, "and creates unnecessary risk for both the President-elect and the prospective nominees."

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Shaub stated that his ethics office had "not been involved in the process as to any of these individuals."

While the ethics office had been in contact with Trump aides during the campaign, Shaub recounted how after the election, the ethics "process we put in place has broken down."

Trump White House officials did not immediately return requests for comment.