(CNN) Former acting Attorney General Sally Yates is alarmed by President Donald Trump's call for the Department of Justice to investigate whether it or the FBI spied on his presidential campaign for political reasons.

"You know, this has really taken the assault on the rule of law to a new level," Yates told David Axelrod in a televised episode of "The Axe Files," airing Saturday at 7 pm ET.

"Really from the beginning of his presidency, President Trump has not observed the time-honored norm that's been in place at least since Watergate that there should be a real division between the Department of Justice and the White House," said Yates, who was fired by Trump in January 2017 for refusing to defend the administration's travel ban.

Trump issued his demand for the inquiry by Twitter on Sunday following reports that the FBI dispatched a confidential source to speak with some aides to Trump's presidential campaign about its possible ties to Russia. Later that day, the agency asked its inspector general to expand its review of the Foreign Intelligence Surveillance Act application process into possible impropriety or political bias by the FBI.

Yates condemned the President's demand as an escalation of his efforts to direct the Justice Department's investigative activities "to a different and more dangerous level" that threatened the public's confidence in the agency.

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